Wednesday, June 24, 2009
| | PHP HOME PHP is a powerful tool for making dynamic and interactive Web pages. PHP is the widely-used, free, and efficient alternative to competitors such as Microsoft's ASP. In our PHP tutorial you will learn about PHP, and how to execute scripts on your server. |
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PHP References
At earnbyvideoz you will find complete references of all PHP functions:
- Array functions
- Calendar functions
- Date functions
- Directory functions
- Error functions
- Filesystem functions
- Filter functions
- FTP functions
- HTTP functions
- LibXML functions
- Mail functions
- Math functions
- Misc functions
- MySQL functions
- SimpleXML functions
- String functions
- XML Parser functions
- Zip functions
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PHP is a server-side scripting language.
What You Should Already Know
Before you continue you should have a basic understanding of the following:
- HTML/XHTML
- JavaScript
If you want to study these subjects first, find the tutorials on our Home page.
What is PHP?
- PHP stands for PHP: Hypertext Preprocessor
- PHP is a server-side scripting language, like ASP
- PHP scripts are executed on the server
- PHP supports many databases (MySQL, Informix, Oracle, Sybase, Solid, PostgreSQL, Generic ODBC, etc.)
- PHP is an open source software
- PHP is free to download and use
What is a PHP File?
- PHP files can contain text, HTML tags and scripts
- PHP files are returned to the browser as plain HTML
- PHP files have a file extension of ".php", ".php3", or ".phtml"
What is MySQL?
- MySQL is a database server
- MySQL is ideal for both small and large applications
- MySQL supports standard SQL
- MySQL compiles on a number of platforms
- MySQL is free to download and use
PHP + MySQL
- PHP combined with MySQL are cross-platform (you can develop in Windows and serve on a Unix platform)
Why PHP?
- PHP runs on different platforms (Windows, Linux, Unix, etc.)
- PHP is compatible with almost all servers used today (Apache, IIS, etc.)
- PHP is FREE to download from the official PHP resource: www.php.net
- PHP is easy to learn and runs efficiently on the server side
Where to Start?
To get access to a web server with PHP support, you can:
- Install Apache (or IIS) on your own server, install PHP, and MySQL
- Or find a web hosting plan with PHP and MySQL support
What do you Need?
If your server supports PHP you don't need to do anything.
Just create some .php files in your web directory, and the server will parse them for you. Because it is free, most web hosts offer PHP support.
However, if your server does not support PHP, you must install PHP.
Here is a link to a good tutorial from PHP.net on how to install PHP5: http://www.php.net/manual/en/install.php
Download PHP
Download PHP for free here: http://www.php.net/downloads.php
Download MySQL Database
Download MySQL for free here: http://www.mysql.com/downloads/index.html
Download Apache Server
Download Apache for free here: http://httpd.apache.org/download.cgi
PHP code is executed on the server, and the plain HTML result is sent to the browser.
Basic PHP Syntax
A PHP scripting block always starts with and ends with ?>. A PHP scripting block can be placed anywhere in the document.
On servers with shorthand support enabled you can start a scripting block with .
For maximum compatibility, we recommend that you use the standard form (
____________________________________________________________________
| ?> ____________________________________________________________________ |
A PHP file normally contains HTML tags, just like an HTML file, and some PHP scripting code.
Below, we have an example of a simple PHP script which sends the text "Hello World" to the browser:
____________________________________________________________________
| echo "Hello World"; ?> ____________________________________________________________________ |
Each code line in PHP must end with a semicolon. The semicolon is a separator and is used to distinguish one set of instructions from another.
There are two basic statements to output text with PHP: echo and print. In the example above we have used the echo statement to output the text "Hello World".
Note: The file must have a .php extension. If the file has a .html extension, the PHP code will not be executed.
Comments in PHP
In PHP, we use // to make a single-line comment or /* and */ to make a large comment block.
| ____________________________________________________________________ //This is a comment /* This is a comment block */ ?> ____________________________________________________________________ |
Tuesday, June 23, 2009
A string variable is used to store and manipulate text.
String Variables in PHP
String variables are used for values that contains characters.
In this chapter we are going to look at the most common functions and operators used to manipulate strings in PHP.
After we create a string we can manipulate it. A string can be used directly in a function or it can be stored in a variable.
Below, the PHP script assigns the text "Hello World" to a string variable called $txt:
_________________________________________________________________
____________________________________________________________________ |
The output of the code above will be:
____________________________________________________________________
| Hello World ____________________________________________________________________ |
Now, lets try to use some different functions and operators to manipulate the string.
The Concatenation Operator
There is only one string operator in PHP.
The concatenation operator (.) is used to put two string values together.
To concatenate two string variables together, use the concatenation operator:
____________________________________________________________________
____________________________________________________________________ |
The output of the code above will be:
____________________________________________________________________
| Hello World! What a nice day! ____________________________________________________________________ |
If we look at the code above you see that we used the concatenation operator two times. This is because we had to insert a third string (a space character), to separate the two strings.
The strlen() function
The strlen() function is used to return the length of a string.
Let's find the length of a string:
____________________________________________________________________
____________________________________________________________________ |
The output of the code above will be:
____________________________________________________________________
| 12 ____________________________________________________________________ |
The length of a string is often used in loops or other functions, when it is important to know when the string ends. (i.e. in a loop, we would want to stop the loop after the last character in the string).
The strpos() function
The strpos() function is used to search for character within a string.
If a match is found, this function will return the position of the first match. If no match is found, it will return FALSE.
Let's see if we can find the string "world" in our string:
____________________________________________________________________
____________________________________________________________________ |
The output of the code above will be:
____________________________________________________________________
| 6 ____________________________________________________________________ |
The position of the string "world" in our string is position 6. The reason that it is 6 (and not 7), is that the first position in the string is 0, and not 1.
Complete PHP String Reference
For a complete reference of all string functions, go to our complete PHP String Reference.
The reference contains a brief description, and examples of use, for each function!
Operators are used to operate on values.
PHP Operators
This section lists the different operators used in PHP.
Arithmetic Operators
| Operator | Description | Example | Result |
|---|---|---|---|
| + | Addition | x=2 x+2 | 4 |
| - | Subtraction | x=2 5-x | 3 |
| * | Multiplication | x=4 x*5 | 20 |
| / | Division | 15/5 5/2 | 3 2.5 |
| % | Modulus (division remainder) | 5%2 10%8 10%2 | 1 2 0 |
| ++ | Increment | x=5 x++ | x=6 |
| -- | Decrement | x=5 x-- | x=4 |
Assignment Operators
| Operator | Example | Is The Same As |
|---|---|---|
| = | x=y | x=y |
| += | x+=y | x=x+y |
| -= | x-=y | x=x-y |
| *= | x*=y | x=x*y |
| /= | x/=y | x=x/y |
| .= | x.=y | x=x.y |
| %= | x%=y | x=x%y |
Comparison Operators
| Operator | Description | Example |
|---|---|---|
| == | is equal to | 5==8 returns false |
| != | is not equal | 5!=8 returns true |
| > | is greater than | 5>8 returns false |
| < | is less than | 5<8> |
| >= | is greater than or equal to | 5>=8 returns false |
| <= | is less than or equal to | 5<=8 returns true |
Logical Operators
| Operator | Description | Example |
|---|---|---|
| && | and | x=6 y=3 (x <> 1) returns true |
| || | or | x=6 y=3 (x==5 || y==5) returns false |
| ! | not | x=6 y=3 !(x==y) returns true |
Conditional statements are used to perform different actions based on different conditions.
Conditional Statements
Very often when you write code, you want to perform different actions for different decisions.
You can use conditional statements in your code to do this.
In PHP we have the following conditional statements:
- if statement - use this statement to execute some code only if a specified condition is true
- if...else statement - use this statement to execute some code if a condition is true and another code if the condition is false
- if...elseif....else statement - use this statement to select one of several blocks of code to be executed
- switch statement - use this statement to select one of many blocks of code to be executed
The if Statement
Use the if statement to execute some code only if a specified condition is true.
Syntax
____________________________________________________________________| if (condition) code to be executed if condition is true; ____________________________________________________________________ |
The following example will output "Have a nice weekend!" if the current day is Friday:
| ____________________________________________________________________ $d=date("D"); if ($d=="Fri") echo "Have a nice weekend!"; ?> ____________________________________________________________________ |
Notice that there is no ..else.. in this syntax. You tell the browser to execute some code only if the specified condition is true.
The if...else Statement
Use the if....else statement to execute some code if a condition is true and another code if a condition is false.
Syntax
____________________________________________________________________| if (condition) code to be executed if condition is true; else code to be executed if condition is false; ____________________________________________________________________ |
Example
The following example will output "Have a nice weekend!" if the current day is Friday, otherwise it will output "Have a nice day!":
| ____________________________________________________________________ $d=date("D"); if ($d=="Fri") echo "Have a nice weekend!"; else echo "Have a nice day!"; ?> ____________________________________________________________________ |
If more than one line should be executed if a condition is true/false, the lines should be enclosed within curly braces:
| ____________________________________________________________________ $d=date("D"); if ($d=="Fri") { echo "Hello! "; echo "Have a nice weekend!"; echo "See you on Monday!"; } ?> ____________________________________________________________________ |
The if...elseif....else Statement
Use the if....elseif...else statement to select one of several blocks of code to be executed.
Syntax
____________________________________________________________________| if (condition) code to be executed if condition is true; elseif (condition) code to be executed if condition is true; else code to be executed if condition is false; ____________________________________________________________________ |
Example
The following example will output "Have a nice weekend!" if the current day is Friday, and "Have a nice Sunday!" if the current day is Sunday. Otherwise it will output "Have a nice day!":
| ____________________________________________________________________ $d=date("D"); if ($d=="Fri") echo "Have a nice weekend!"; elseif ($d=="Sun") echo "Have a nice Sunday!"; else echo "Have a nice day!"; ?> ____________________________________________________________________ |
Conditional statements are used to perform different actions based on different conditions.
The PHP Switch Statement
Use the switch statement to select one of many blocks of code to be executed.
Syntax
____________________________________________________________________| switch (n) { case label1: code to be executed if n=label1; break; case label2: code to be executed if n=label2; break; default: code to be executed if n is different from both label1 and label2; } ____________________________________________________________________ |
This is how it works: First we have a single expression n (most often a variable), that is evaluated once. The value of the expression is then compared with the values for each case in the structure. If there is a match, the block of code associated with that case is executed. Use break to prevent the code from running into the next case automatically. The default statement is used if no match is found.
Example
____________________________________________________________________switch ($x)
{
case 1:
echo "Number 1";
break;
case 2:
echo "Number 2";
break;
case 3:
echo "Number 3";
break;
default:
echo "No number between 1 and 3";
}
?>
____________________________________________________________________
An array stores multiple values in a single variable.
What is an Array?
You have already learnt that a variable is a storage area holding numbers and text. The problem is, a variable will hold only one value.
An array is a special variable, which can hold more than one value, at a time.
If you have a list of items (a list of car names, for example), storing the cars in single variables could look like this:
____________________________________________________________________
| $cars1="Saab"; $cars2="Volvo"; $cars3="BMW"; ____________________________________________________________________ |
However, what if you want to loop through the cars and find a specific one? And what if you had not 3 cars, but 300?
The best solution here is to use an array!
An array can hold all your variable values under a single name. And you can access the values by referring to the array name.
Each element in the array has its own index so that it can be easily accessed.
In PHP, there are three kind of arrays:
- Numeric array - An array with a numeric index
- Associative array - An array where each ID key is associated with a value
- Multidimensional array - An array containing one or more arrays
Numeric Arrays
A numeric array stores each array element with a numeric index.
There are two methods to create a numeric array.
1. In the following example the index are automatically assigned (the index starts at 0):
____________________________________________________________________
| $cars=array("Saab","Volvo","BMW","Toyota"); ____________________________________________________________________ |
2. In the following example we assign the index manually:
___________________________________________________________________
| $cars[0]="Saab"; $cars[1]="Volvo"; $cars[2]="BMW"; $cars[3]="Toyota"; ___________________________________________________________________ |
Example
In the following example you access the variable values by referring to the array name and index:
____________________________________________________________________
| $cars[0]="Saab"; $cars[1]="Volvo"; $cars[2]="BMW"; $cars[3]="Toyota"; echo $cars[0] . " and " . $cars[1] . " are Swedish cars."; ?> ____________________________________________________________________ |
The code above will output:
____________________________________________________________________
| Saab and Volvo are Swedish cars. |
Associative Arrays
An associative array, each ID key is associated with a value.
When storing data about specific named values, a numerical array is not always the best way to do it.
With associative arrays we can use the values as keys and assign values to them.
Example 1
In this example we use an array to assign ages to the different persons:
____________________________________________________________________
| $ages = array("Peter"=>32, "Quagmire"=>30, "Joe"=>34); ____________________________________________________________________ |
Example 2
This example is the same as example 1, but shows a different way of creating the array:
____________________________________________________________________
| $ages['Peter'] = "32"; $ages['Quagmire'] = "30"; $ages['Joe'] = "34"; ____________________________________________________________________ |
The ID keys can be used in a script:
____________________________________________________________________
| $ages['Peter'] = "32"; $ages['Quagmire'] = "30"; $ages['Joe'] = "34"; echo "Peter is " . $ages['Peter'] . " years old."; ?> ____________________________________________________________________ |
The code above will output:
____________________________________________________________________
| Peter is 32 years old. |
Multidimensional Arrays
In a multidimensional array, each element in the main array can also be an array. And each element in the sub-array can be an array, and so on.
Example
In this example we create a multidimensional array, with automatically assigned ID keys:
____________________________________________________________________
| $families = array ( "Griffin"=>array ( "Peter", "Lois", "Megan" ), "Quagmire"=>array ( "Glenn" ), "Brown"=>array ( "Cleveland", "Loretta", "Junior" ) ); ____________________________________________________________________ |
The array above would look like this if written to the output:
____________________________________________________________________
| Array ( [Griffin] => Array ( [0] => Peter [1] => Lois [2] => Megan ) [Quagmire] => Array ( [0] => Glenn ) [Brown] => Array ( [0] => Cleveland [1] => Loretta [2] => Junior ) ) ____________________________________________________________________ |
Example 2
Lets try displaying a single value from the array above:
____________________________________________________________________
| echo "Is " . $families['Griffin'][2] . " a part of the Griffin family?"; ____________________________________________________________________ |
The code above will output:
____________________________________________________________________
| Is Megan a part of the Griffin family? ____________________________________________________________________ |
Loops execute a block of code a specified number of times, or while a specified condition is true.
PHP Loops
Often when you write code, you want the same block of code to run over and over again in a row. Instead of adding several almost equal lines in a script we can use loops to perform a task like this.
In PHP, we have the following looping statements:
- while - loops through a block of code while a specified condition is true
- do...while - loops through a block of code once, and then repeats the loop as long as a specified condition is true
- for - loops through a block of code a specified number of times
- foreach - loops through a block of code for each element in an array
The while Loop
The while loop executes a block of code while a condition is true.
Syntax
____________________________________________________________________| while (condition) { code to be executed; } ____________________________________________________________________ |
Example
The example below defines a loop that starts with i=1. The loop will continue to run as long as i is less than, or equal to 5. i will increase by 1 each time the loop runs:
| ____________________________________________________________________ $i=1; while($i<=5) { echo "The number is " . $i . " "; $i++; } ?> ____________________________________________________________________ |
Output:
____________________________________________________________________
| The number is 1 The number is 2 The number is 3 The number is 4 The number is 5 ____________________________________________________________________ |
The do...while Statement
The do...while statement will always execute the block of code once, it will then check the condition, and repeat the loop while the condition is true.
Syntax
____________________________________________________________________| do { code to be executed; } while (condition); ____________________________________________________________________ |
Example
The example below defines a loop that starts with i=1. It will then increment i with 1, and write some output. Then the condition is checked, and the loop will continue to run as long as i is less than, or equal to 5:
| ____________________________________________________________________ $i=1; do { $i++; echo "The number is " . $i . " "; } while ($i<=5); ?> ____________________________________________________________________ |
Output:
____________________________________________________________________
| The number is 2 The number is 3 The number is 4 The number is 5 The number is 6 ____________________________________________________________________ |
The for loop and the foreach loop will be explained in the next chapter.
Loops execute a block of code a specified number of times, or while a specified condition is true.
The for Loop
The for loop is used when you know in advance how many times the script should run.
Syntax
____________________________________________________________________| for (init; condition; increment) { code to be executed; } ____________________________________________________________________ |
Parameters:
- init: Mostly used to set a counter (but can be any code to be executed once at the beginning of the loop)
- condition: Evaluated for each loop iteration. If it evaluates to TRUE, the loop continues. If it evaluates to FALSE, the loop ends.
- increment: Mostly used to increment a counter (but can be any code to be executed at the end of the loop)
Note: Each of the parameters above can be empty, or have multiple expressions (separated by commas).
Example
The example below defines a loop that starts with i=1. The loop will continue to run as long as i is less than, or equal to 5. i will increase by 1 each time the loop runs:
| ____________________________________________________________________ for ($i=1; $i<=5; $i++) { echo "The number is " . $i . " "; } ?> ____________________________________________________________________ |
Output:
____________________________________________________________________
| The number is 1 The number is 2 The number is 3 The number is 4 The number is 5 |
The foreach Loop
The foreach loop is used to loop through arrays.
Syntax
____________________________________________________________________| foreach ($array as $value) { code to be executed; } ____________________________________________________________________ |
For every loop iteration, the value of the current array element is assigned to $value (and the array pointer is moved by one) - so on the next loop iteration, you'll be looking at the next array value.
Example
The following example demonstrates a loop that will print the values of the given array:
| ____________________________________________________________________ $x=array("one","two","three"); foreach ($x as $value) { echo $value . " "; } ?> ____________________________________________________________________ |
Output:
____________________________________________________________________
| one two three ____________________________________________________________________ |
The real power of PHP comes from its functions.
In PHP, there are more than 700 built-in functions.
PHP Built-in Functions
For a complete reference and examples of the built-in functions, please visit our PHP Reference.
PHP Functions
In this chapter we will show you how to create your own functions.
To keep the browser from executing a script when the page loads, you can put your script into a function.
A function will be executed by a call to the function.
You may call a function from anywhere within a page.
Create a PHP Function
A function will be executed by a call to the function.
Syntax
____________________________________________________________________| function functionName() { code to be executed; } ____________________________________________________________________ |
PHP function guidelines:
- Give the function a name that reflects what the function does
- The function name can start with a letter or underscore (not a number)
Example
A simple function that writes my name when it is called:
| ____________________________________________________________________ function writeName() { echo "Kai Jim Refsnes"; } echo "My name is "; writeName(); ?> ____________________________________________________________________ |
Output:
____________________________________________________________________
| My name is Kai Jim Refsnes |
PHP Functions - Adding parameters
To add more functionality to a function, we can add parameters. A parameter is just like a variable.
Parameters are specified after the function name, inside the parentheses.
Example 1
The following example will write different first names, but equal last name:
| ____________________________________________________________________ function writeName($fname) { echo $fname . " Refsnes. "; } echo "My name is "; writeName("Kai Jim"); echo "My sister's name is "; writeName("Hege"); echo "My brother's name is "; writeName("Stale"); ?> ____________________________________________________________________ |
Output:
____________________________________________________________________
| My name is Kai Jim Refsnes. My sister's name is Hege Refsnes. My brother's name is Stale Refsnes. ____________________________________________________________________ |
Example 2
The following function has two parameters:
| ____________________________________________________________________ function writeName($fname,$punctuation) { echo $fname . " Refsnes" . $punctuation . " "; } echo "My name is "; writeName("Kai Jim","."); echo "My sister's name is "; writeName("Hege","!"); echo "My brother's name is "; writeName("Ståle","?"); ?> ____________________________________________________________________ |
Output:
____________________________________________________________________
| My name is Kai Jim Refsnes. My sister's name is Hege Refsnes! My brother's name is Ståle Refsnes? ____________________________________________________________________ |
PHP Functions - Return values
To let a function return a value, use the return statement.
Example
| ____________________________________________________________________ function add($x,$y) { $total=$x+$y; return $total; } echo "1 + 16 = " . add(1,16); ?> ____________________________________________________________________ |
Output:
____________________________________________________________________
| 1 + 16 = 17 ____________________________________________________________________ |
The PHP $_GET and $_POST variables are used to retrieve information from forms, like user input.
PHP Form Handling
The most important thing to notice when dealing with HTML forms and PHP is that any form element in an HTML page will automatically be available to your PHP scripts.
Example
The example below contains an HTML form with two input fields and a submit button:
| ____________________________________________________________________ ____________________________________________________________________ |
When a user fills out the form above and click on the submit button, the form data is sent to a PHP file, called "welcome.php":
"welcome.php" looks like this:
| ____________________________________________________________________ Welcome ! You are years old. ____________________________________________________________________ |
Output could be something like this:
____________________________________________________________________
| Welcome John! You are 28 years old. ____________________________________________________________________ |
The PHP $_GET and $_POST functions will be explained in the next chapters.
Form Validation
User input should be validated on the browser whenever possible (by client scripts). Browser validation is faster and reduces the server load.
You should consider server validation if the user input will be inserted into a database. A good way to validate a form on the server is to post the form to itself, instead of jumping to a different page. The user will then get the error messages on the same page as the form. This makes it easier to discover the error.
The built-in $_GET function is used to collect values in a form with method="get".
The $_GET Function
The built-in $_GET function is used to collect values from a form sent with method="get".
Information sent from a form with the GET method is visible to everyone (it will be displayed in the browser's address bar) and has limits on the amount of information to send (max. 100 characters).
Example
____________________________________________________________________| ____________________________________________________________________ |
When the user clicks the "Submit" button, the URL sent to the server could look something like this:
____________________________________________________________________
| http://www.learnbyvideoz.blogspot.com/ ____________________________________________________________________ |
The "welcome.php" file can now use the $_GET function to collect form data (the names of the form fields will automatically be the keys in the $_GET array):
____________________________________________________________________
| Welcome . You are years old! |
____________________________________________________________________
When to use method="get"?
When using method="get" in HTML forms, all variable names and values are displayed in the URL.
Note: This method should not be used when sending passwords or other sensitive information!
However, because the variables are displayed in the URL, it is possible to bookmark the page. This can be useful in some cases.
Note: The get method is not suitable for large variable values; the value cannot exceed 100 characters.
The built-in $_POST function is used to collect values in a form with method="post".
The $_POST Function
The built-in $_POST function is used to collect values from a form sent with method="post".
Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send.
Note: However, there is an 8 Mb max size for the POST method, by default (can be changed by setting the post_max_size in the php.ini file).
Example
____________________________________________________________________| ____________________________________________________________________ |
When the user clicks the "Submit" button, the URL will look like this:
____________________________________________________________________
| http://www.learnbyvideoz.blogspot.com/welcome.php ____________________________________________________________________ |
The "welcome.php" file can now use the $_POST function to collect form data (the names of the form fields will automatically be the keys in the $_POST array):
____________________________________________________________________
| Welcome ! You are years old. |
When to use method="post"?
Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send.
However, because the variables are not displayed in the URL, it is not possible to bookmark the page.
The PHP $_REQUEST Function
The PHP built-in $_REQUEST function contains the contents of both $_GET, $_POST, and $_COOKIE.
The $_REQUEST function can be used to collect form data sent with both the GET and POST methods.
Example
____________________________________________________________________| Welcome ! You are years old. ____________________________________________________________________ |
PHP Advanced
The PHP date() function is used to format a time and/or date.
The PHP Date() Function
The PHP date() function formats a timestamp to a more readable date and time.
A timestamp is a sequence of characters, denoting the date and/or time at which a certain event occurred.
Syntax
____________________________________________________________________| date(format,timestamp) |
| Parameter | Description |
|---|---|
| format | Required. Specifies the format of the timestamp |
| timestamp | Optional. Specifies a timestamp. Default is the current date and time |
PHP Date() - Format the Date
The required format parameter in the date() function specifies how to format the date/time.
Here are some characters that can be used:
- d - Represents the day of the month (01 to 31)
- m - Represents a month (01 to 12)
- Y - Represents a year (in four digits)
A list of all the characters that can be used in the format parameter, can be found in our PHP Date reference.
Other characters, like"/", ".", or "-" can also be inserted between the letters to add additional formatting:
____________________________________________________________________
| echo date("Y/m/d") . " "; echo date("Y.m.d") . " "; echo date("Y-m-d") ?> ____________________________________________________________________ |
The output of the code above could be something like this:
____________________________________________________________________
| 2009/05/11 2009.05.11 2009-05-11 |
PHP Date() - Adding a Timestamp
The optional timestamp parameter in the date() function specifies a timestamp. If you do not specify a timestamp, the current date and time will be used.
The mktime() function returns the Unix timestamp for a date.
The Unix timestamp contains the number of seconds between the Unix Epoch (January 1 1970 00:00:00 GMT) and the time specified.
Syntax for mktime()
____________________________________________________________________| mktime(hour,minute,second,month,day,year,is_dst) ____________________________________________________________________ |
To go one day in the future we simply add one to the day argument of mktime():
____________________________________________________________________
| $tomorrow = mktime(0,0,0,date("m"),date("d")+1,date("Y")); echo "Tomorrow is ".date("Y/m/d", $tomorrow); ?> ____________________________________________________________________ |
The output of the code above could be something like this:
____________________________________________________________________
| Tomorrow is 2009/05/12 |
PHP Date - Reference
For more information about all the built-in PHP date functions, please visit our PHP Date Reference.
Server Side Includes (SSI)
You can insert the content of one PHP file into another PHP file before the server executes it, with the include() or require() function.
The two functions are identical in every way, except how they handle errors:
- include() generates a warning, but the script will continue execution
- require() generates a fatal error, and the script will stop
These two functions are used to create functions, headers, footers, or elements that will be reused on multiple pages.
Server side includes saves a lot of work. This means that you can create a standard header, footer, or menu file for all your web pages. When the header needs to be updated, you can only update the include file, or when you add a new page to your site, you can simply change the menu file (instead of updating the links on all your web pages).
PHP include() Function
The include() function takes all the content in a specified file and includes it in the current file.
If an error occurs, the include() function generates a warning, but the script will continue execution.
Example 1
Assume that you have a standard header file, called "header.php". To include the header file in a page, use the include() function:
____________________________________________________________________Welcome to my home page!Some text. ____________________________________________________________________ |
Example 2
Assume we have a standard menu file, called "menu.php", that should be used on all pages:
____________________________________________________________________
| Home Tutorials References Examples About Us Contact Us ____________________________________________________________________ |
All pages in the Web site should include this menu file. Here is how it can be done:
____________________________________________________________________Welcome to my home page.Some text. ____________________________________________________________________ |
If you look at the source code of the page above (in a browser), it will look like this:
____________________________________________________________________Welcome to my home page!Some text. ____________________________________________________________________ |
PHP require() Function
The require() function is identical to include(), except that it handles errors differently.
If an error occurs, the include() function generates a warning, but the script will continue execution. The require() generates a fatal error, and the script will stop.
Error Example include() Function
| ____________________________________________________________________ include("wrongFile.php"); echo "Hello World!"; ?> ____________________________________________________________________ |
Error message:
____________________________________________________________________
| Warning: include(wrongFile.php) [function.include]: failed to open stream: No such file or directory in C:\home\website\test.php on line 5 Warning: include() [function.include]: Failed opening 'wrongFile.php' for inclusion (include_path='.;C:\php5\pear') in C:\home\website\test.php on line 5 Hello World! ____________________________________________________________________ |
Notice that the echo statement is executed! This is because a Warning does not stop the script execution.
Error Example require() Function
Now, let's run the same example with the require() function.
| ____________________________________________________________________ require("wrongFile.php"); echo "Hello World!"; ?> ____________________________________________________________________ |
Error message:
____________________________________________________________________
| Warning: require(wrongFile.php) [function.require]: failed to open stream: No such file or directory in C:\home\website\test.php on line 5 Fatal error: require() [function.require]: Failed opening required 'wrongFile.php' (include_path='.;C:\php5\pear') in C:\home\website\test.php on line 5 ____________________________________________________________________ |
The echo statement is not executed, because the script execution stopped after the fatal error.
It is recommended to use the require() function instead of include(), because scripts should not continue after an error.
The fopen() function is used to open files in PHP.
Opening a File
The fopen() function is used to open files in PHP.
The first parameter of this function contains the name of the file to be opened and the second parameter specifies in which mode the file should be opened:
| ____________________________________________________________________ $file=fopen("welcome.txt","r"); ?> ____________________________________________________________________ |
The file may be opened in one of the following modes:
| Modes | Description |
|---|---|
| r | Read only. Starts at the beginning of the file |
| r+ | Read/Write. Starts at the beginning of the file |
| w | Write only. Opens and clears the contents of file; or creates a new file if it doesn't exist |
| w+ | Read/Write. Opens and clears the contents of file; or creates a new file if it doesn't exist |
| a | Append. Opens and writes to the end of the file or creates a new file if it doesn't exist |
| a+ | Read/Append. Preserves file content by writing to the end of the file |
| x | Write only. Creates a new file. Returns FALSE and an error if file already exists |
| x+ | Read/Write. Creates a new file. Returns FALSE and an error if file already exists |
Note: If the fopen() function is unable to open the specified file, it returns 0 (false).
Example
The following example generates a message if the fopen() function is unable to open the specified file:
| ____________________________________________________________________ $file=fopen("welcome.txt","r") or exit("Unable to open file!"); ?> ____________________________________________________________________ |
Closing a File
The fclose() function is used to close an open file:
____________________________________________________________________
| $file = fopen("test.txt","r"); //some code to be executed fclose($file); ?> |
Check End-of-file
The feof() function checks if the "end-of-file" (EOF) has been reached.
The feof() function is useful for looping through data of unknown length.
Note: You cannot read from files opened in w, a, and x mode!
____________________________________________________________________
| if (feof($file)) echo "End of file"; |
Reading a File Line by Line
The fgets() function is used to read a single line from a file.
Note: After a call to this function the file pointer has moved to the next line.
Example
The example below reads a file line by line, until the end of file is reached:
____________________________________________________________________
| $file = fopen("welcome.txt", "r") or exit("Unable to open file!"); //Output a line of the file until the end is reached while(!feof($file)) { echo fgets($file). " "; } fclose($file); ?> |
Reading a File Character by Character
The fgetc() function is used to read a single character from a file.
Note: After a call to this function the file pointer moves to the next character.
Example
The example below reads a file character by character, until the end of file is reached:
____________________________________________________________________
| $file=fopen("welcome.txt","r") or exit("Unable to open file!"); while (!feof($file)) { echo fgetc($file); } fclose($file); ?> |
PHP Filesystem Reference
For a full reference of the PHP filesystem functions, visit our PHP Filesystem Reference.
With PHP, it is possible to upload files to the server.
Create an Upload-File Form
To allow users to upload files from a form can be very useful.
Look at the following HTML form for uploading files:
| ____________________________________________________________________ enctype="multipart/form-data"> ____________________________________________________________________ |
Notice the following about the HTML form above:
- The enctype attribute of the tag specifies which content-type to use when submitting the form. "multipart/form-data" is used when a form requires binary data, like the contents of a file, to be uploaded
- The type="file" attribute of the tag specifies that the input should be processed as a file. For example, when viewed in a browser, there will be a browse-button next to the input field
Note: Allowing users to upload files is a big security risk. Only permit trusted users to perform file uploads.
Create The Upload Script
The "upload_file.php" file contains the code for uploading a file:
____________________________________________________________________
| if ($_FILES["file"]["error"] > 0) { echo "Error: " . $_FILES["file"]["error"] . " "; } else { echo "Upload: " . $_FILES["file"]["name"] . " "; echo "Type: " . $_FILES["file"]["type"] . " "; echo "Size: " . ($_FILES["file"]["size"] / 1024) . " Kb "; echo "Stored in: " . $_FILES["file"]["tmp_name"]; } ?> ____________________________________________________________________ |
By using the global PHP $_FILES array you can upload files from a client computer to the remote server.
The first parameter is the form's input name and the second index can be either "name", "type", "size", "tmp_name" or "error". Like this:
- $_FILES["file"]["name"] - the name of the uploaded file
- $_FILES["file"]["type"] - the type of the uploaded file
- $_FILES["file"]["size"] - the size in bytes of the uploaded file
- $_FILES["file"]["tmp_name"] - the name of the temporary copy of the file stored on the server
- $_FILES["file"]["error"] - the error code resulting from the file upload
This is a very simple way of uploading files. For security reasons, you should add restrictions on what the user is allowed to upload.
Restrictions on Upload
In this script we add some restrictions to the file upload. The user may only upload .gif or .jpeg files and the file size must be under 20 kb:
____________________________________________________________________
| if ((($_FILES["file"]["type"] == "image/gif") || ($_FILES["file"]["type"] == "image/jpeg") || ($_FILES["file"]["type"] == "image/pjpeg")) && ($_FILES["file"]["size"] < 20000)) { if ($_FILES["file"]["error"] > 0) { echo "Error: " . $_FILES["file"]["error"] . " "; } else { echo "Upload: " . $_FILES["file"]["name"] . " "; echo "Type: " . $_FILES["file"]["type"] . " "; echo "Size: " . ($_FILES["file"]["size"] / 1024) . " Kb "; echo "Stored in: " . $_FILES["file"]["tmp_name"]; } } else { echo "Invalid file"; } ?> ____________________________________________________________________ |
Note: For IE to recognize jpg files the type must be pjpeg, for FireFox it must be jpeg.
Saving the Uploaded File
The examples above create a temporary copy of the uploaded files in the PHP temp folder on the server.
The temporary copied files disappears when the script ends. To store the uploaded file we need to copy it to a different location:
____________________________________________________________________
| if ((($_FILES["file"]["type"] == "image/gif") || ($_FILES["file"]["type"] == "image/jpeg") || ($_FILES["file"]["type"] == "image/pjpeg")) && ($_FILES["file"]["size"] < 20000)) { if ($_FILES["file"]["error"] > 0) { echo "Return Code: " . $_FILES["file"]["error"] . " "; } else { echo "Upload: " . $_FILES["file"]["name"] . " "; echo "Type: " . $_FILES["file"]["type"] . " "; echo "Size: " . ($_FILES["file"]["size"] / 1024) . " Kb "; echo "Temp file: " . $_FILES["file"]["tmp_name"] . " "; if (file_exists("upload/" . $_FILES["file"]["name"])) { echo $_FILES["file"]["name"] . " already exists. "; } else { move_uploaded_file($_FILES["file"]["tmp_name"], "upload/" . $_FILES["file"]["name"]); echo "Stored in: " . "upload/" . $_FILES["file"]["name"]; } } } else { echo "Invalid file"; } ?> ____________________________________________________________________ |
The script above checks if the file already exists, if it does not, it copies the file to the specified folder.
Note: This example saves the file to a new folder called "upload"
A cookie is often used to identify a user.
What is a Cookie?
A cookie is often used to identify a user. A cookie is a small file that the server embeds on the user's computer. Each time the same computer requests a page with a browser, it will send the cookie too. With PHP, you can both create and retrieve cookie values.
How to Create a Cookie?
The setcookie() function is used to set a cookie.
Note: The setcookie() function must appear BEFORE the tag.
Syntax
___________________________________________________________________| setcookie(name, value, expire, path, domain); ___________________________________________________________________ |
Example 1
In the example below, we will create a cookie named "user" and assign the value "Alex Porter" to it. We also specify that the cookie should expire after one hour:
____________________________________________________________________
| setcookie("user", "Alex Porter", time()+3600); ?> ..... ____________________________________________________________________ |
Note: The value of the cookie is automatically URLencoded when sending the cookie, and automatically decoded when received (to prevent URLencoding, use setrawcookie() instead).
Example 2
You can also set the expiration time of the cookie in another way. It may be easier than using seconds.
____________________________________________________________________
| $expire=time()+60*60*24*30; setcookie("user", "Alex Porter", $expire); ?> ..... ____________________________________________________________________ |
In the example above the expiration time is set to a month (60 sec * 60 min * 24 hours * 30 days).
How to Retrieve a Cookie Value?
The PHP $_COOKIE variable is used to retrieve a cookie value.
In the example below, we retrieve the value of the cookie named "user" and display it on a page:
____________________________________________________________________
| // Print a cookie echo $_COOKIE["user"]; // A way to view all cookies print_r($_COOKIE); ?> ____________________________________________________________________ |
In the following example we use the isset() function to find out if a cookie has been set:
| ____________________________________________________________________ if (isset($_COOKIE["user"])) echo "Welcome " . $_COOKIE["user"] . "! "; else echo "Welcome guest! "; ?> ____________________________________________________________________ |
How to Delete a Cookie?
When deleting a cookie you should assure that the expiration date is in the past.
Delete example:
____________________________________________________________________
| // set the expiration date to one hour ago setcookie("user", "", time()-3600); ?> ____________________________________________________________________ |
What if a Browser Does NOT Support Cookies?
If your application deals with browsers that do not support cookies, you will have to use other methods to pass information from one page to another in your application. One method is to pass the data through forms (forms and user input are described earlier in this tutorial).
The form below passes the user input to "welcome.php" when the user clicks on the "Submit" button:
| ____________________________________________________________________ ____________________________________________________________________ |
Retrieve the values in the "welcome.php" file like this:
| ____________________________________________________________________ Welcome . You are years old. ____________________________________________________________________ |
A PHP session variable is used to store information about, or change settings for a user session. Session variables hold information about one single user, and are available to all pages in one application.
PHP Session Variables
When you are working with an application, you open it, do some changes and then you close it. This is much like a Session. The computer knows who you are. It knows when you start the application and when you end. But on the internet there is one problem: the web server does not know who you are and what you do because the HTTP address doesn't maintain state.
A PHP session solves this problem by allowing you to store user information on the server for later use (i.e. username, shopping items, etc). However, session information is temporary and will be deleted after the user has left the website. If you need a permanent storage you may want to store the data in a database.
Sessions work by creating a unique id (UID) for each visitor and store variables based on this UID. The UID is either stored in a cookie or is propagated in the URL.
Starting a PHP Session
Before you can store user information in your PHP session, you must first start up the session.
Note: The session_start() function must appear BEFORE the tag:
____________________________________________________________________
| ____________________________________________________________________ |
The code above will register the user's session with the server, allow you to start saving user information, and assign a UID for that user's session.
Storing a Session Variable
The correct way to store and retrieve session variables is to use the PHP $_SESSION variable:
____________________________________________________________________
| session_start(); // store session data $_SESSION['views']=1; ?> //retrieve session data echo "Pageviews=". $_SESSION['views']; ?> ____________________________________________________________________ |
Output:
| Pageviews=1 |
In the example below, we create a simple page-views counter. The isset() function checks if the "views" variable has already been set. If "views" has been set, we can increment our counter. If "views" doesn't exist, we create a "views" variable, and set it to 1:
____________________________________________________________________
| session_start(); if(isset($_SESSION['views'])) $_SESSION['views']=$_SESSION['views']+1; else $_SESSION['views']=1; echo "Views=". $_SESSION['views']; ?> ____________________________________________________________________ |
Destroying a Session
If you wish to delete some session data, you can use the unset() or the session_destroy() function.
The unset() function is used to free the specified session variable:
___________________________________________________________________
| unset($_SESSION['views']); ?> ___________________________________________________________________ |
You can also completely destroy the session by calling the session_destroy() function:
____________________________________________________________________
| session_destroy(); ?> ___________________________________________________________________ |
Note: session_destroy() will reset your session and you will lose all your stored session data.
PHP allows you to send e-mails directly from a script.
The PHP mail() Function
The PHP mail() function is used to send emails from inside a script.
Syntax
______________________________________________________________
| mail(to,subject,message,headers,parameters) |
| Parameter | Description |
|---|---|
| to | Required. Specifies the receiver / receivers of the email |
| subject | Required. Specifies the subject of the email. Note: This parameter cannot contain any newline characters |
| message | Required. Defines the message to be sent. Each line should be separated with a LF (\n). Lines should not exceed 70 characters |
| headers | Optional. Specifies additional headers, like From, Cc, and Bcc. The additional headers should be separated with a CRLF (\r\n) |
| parameters | Optional. Specifies an additional parameter to the sendmail program |
Note: For the mail functions to be available, PHP requires an installed and working email system. The program to be used is defined by the configuration settings in the php.ini file. Read more in our PHP Mail reference.
PHP Simple E-Mail
The simplest way to send an email with PHP is to send a text email.
In the example below we first declare the variables ($to, $subject, $message, $from, $headers), then we use the variables in the mail() function to send an e-mail:
____________________________________________________________________
| $to = "someone@example.com"; $subject = "Test mail"; $message = "Hello! This is a simple email message."; $from = "someonelse@example.com"; $headers = "From: $from"; mail($to,$subject,$message,$headers); echo "Mail Sent."; ?> ____________________________________________________________________ |
PHP Mail Form
With PHP, you can create a feedback-form on your website. The example below sends a text message to a specified e-mail address:
| ____________________________________________________________________ if (isset($_REQUEST['email'])) //if "email" is filled out, send email { //send email $email = $_REQUEST['email'] ; $subject = $_REQUEST['subject'] ; $message = $_REQUEST['message'] ; mail( "someone@example.com", "Subject: $subject", $message, "From: $email" ); echo "Thank you for using our mail form"; } else //if "email" is not filled out, display the form { echo ""; } ?> ____________________________________________________________________ |
This is how the example above works:
- First, check if the email input field is filled out
- If it is not set (like when the page is first visited); output the HTML form
- If it is set (after the form is filled out); send the email from the form
- When submit is pressed after the form is filled out, the page reloads, sees that the email input is set, and sends the email
Note: This is the simplest way to send e-mail, but it is not secure. In the next chapter of this tutorial you can read more about vulnerabilities in e-mail scripts, and how to validate user input to make it more secure.
PHP Mail Reference
For more information about the PHP mail() function, visit our PHP Mail Reference.
PHP E-mail Injections
First, look at the PHP code from the previous chapter:
| ____________________________________________________________________ if (isset($_REQUEST['email'])) //if "email" is filled out, send email { //send email $email = $_REQUEST['email'] ; $subject = $_REQUEST['subject'] ; $message = $_REQUEST['message'] ; mail("someone@example.com", "Subject: $subject", $message, "From: $email" ); echo "Thank you for using our mail form"; } else //if "email" is not filled out, display the form { echo ""; } ?> ____________________________________________________________________ |
The problem with the code above is that unauthorized users can insert data into the mail headers via the input form.
What happens if the user adds the following text to the email input field in the form?
____________________________________________________________________
| someone@example.com%0ACc:person2@example.com %0ABcc:person3@example.com,person3@example.com, anotherperson4@example.com,person5@example.com %0ABTo:person6@example.com ____________________________________________________________________ |
The mail() function puts the text above into the mail headers as usual, and now the header has an extra Cc:, Bcc:, and To: field. When the user clicks the submit button, the e-mail will be sent to all of the addresses above!
PHP Stopping E-mail Injections
The best way to stop e-mail injections is to validate the input.
The code below is the same as in the previous chapter, but now we have added an input validator that checks the email field in the form:
| ____________________________________________________________________ function spamcheck($field) { //filter_var() sanitizes the e-mail //address using FILTER_SANITIZE_EMAIL $field=filter_var($field, FILTER_SANITIZE_EMAIL); //filter_var() validates the e-mail //address using FILTER_VALIDATE_EMAIL if(filter_var($field, FILTER_VALIDATE_EMAIL)) { return TRUE; } else { return FALSE; } } if (isset($_REQUEST['email'])) {//if "email" is filled out, proceed //check if the email address is invalid $mailcheck = spamcheck($_REQUEST['email']); if ($mailcheck==FALSE) { echo "Invalid input"; } else {//send email $email = $_REQUEST['email'] ; $subject = $_REQUEST['subject'] ; $message = $_REQUEST['message'] ; mail("someone@example.com", "Subject: $subject", $message, "From: $email" ); echo "Thank you for using our mail form"; } } else {//if "email" is not filled out, display the form echo ""; } ?> ____________________________________________________________________ |
In the code above we use PHP filters to validate input:
- The FILTER_SANITIZE_EMAIL filter removes all illegal e-mail characters from a string
- The FILTER_VALIDATE_EMAIL filter validates value as an e-mail address
The default error handling in PHP is very simple. An error message with filename, line number and a message describing the error is sent to the browser.
PHP Error Handling
When creating scripts and web applications, error handling is an important part. If your code lacks error checking code, your program may look very unprofessional and you may be open to security risks.
This tutorial contains some of the most common error checking methods in PHP.
We will show different error handling methods:
- Simple "die()" statements
- Custom errors and error triggers
- Error reporting
Basic Error Handling: Using the die() function
The first example shows a simple script that opens a text file:
____________________________________________________________________
| $file=fopen("welcome.txt","r"); ?> ____________________________________________________________________ |
If the file does not exist you might get an error like this:
____________________________________________________________________
| Warning: fopen(welcome.txt) [function.fopen]: failed to open stream: No such file or directory in C:\webfolder\test.php on line 2 ______________________________________________________________ |
To avoid that the user gets an error message like the one above, we test if the file exist before we try to access it:
____________________________________________________________________
| if(!file_exists("welcome.txt")) { die("File not found"); } else { $file=fopen("welcome.txt","r"); } ?> ____________________________________________________________________ |
Now if the file does not exist you get an error like this:
___________________________________________________________________
| File not found ____________________________________________________________________ |
The code above is more efficient than the earlier code, because it uses a simple error handling mechanism to stop the script after the error.
However, simply stopping the script is not always the right way to go. Let's take a look at alternative PHP functions for handling errors.
Creating a Custom Error Handler
Creating a custom error handler is quite simple. We simply create a special function that can be called when an error occurs in PHP.
This function must be able to handle a minimum of two parameters (error level and error message) but can accept up to five parameters (optionally: file, line-number, and the error context):
Syntax
___________________________________________________________________| error_function(error_level,error_message, error_file,error_line,error_context) ___________________________________________________________________ |
| Parameter | Description |
|---|---|
| error_level | Required. Specifies the error report level for the user-defined error. Must be a value number. See table below for possible error report levels |
| error_message | Required. Specifies the error message for the user-defined error |
| error_file | Optional. Specifies the filename in which the error occurred |
| error_line | Optional. Specifies the line number in which the error occurred |
| error_context | Optional. Specifies an array containing every variable, and their values, in use when the error occurred |
Error Report levels
These error report levels are the different types of error the user-defined error handler can be used for:
| Value | Constant | Description |
|---|---|---|
| 2 | E_WARNING | Non-fatal run-time errors. Execution of the script is not halted |
| 8 | E_NOTICE | Run-time notices. The script found something that might be an error, but could also happen when running a script normally |
| 256 | E_USER_ERROR | Fatal user-generated error. This is like an E_ERROR set by the programmer using the PHP function trigger_error() |
| 512 | E_USER_WARNING | Non-fatal user-generated warning. This is like an E_WARNING set by the programmer using the PHP function trigger_error() |
| 1024 | E_USER_NOTICE | User-generated notice. This is like an E_NOTICE set by the programmer using the PHP function trigger_error() |
| 4096 | E_RECOVERABLE_ERROR | Catchable fatal error. This is like an E_ERROR but can be caught by a user defined handle (see also set_error_handler()) |
| 8191 | E_ALL | All errors and warnings, except level E_STRICT (E_STRICT will be part of E_ALL as of PHP 6.0) |
Now lets create a function to handle errors:
___________________________________________________________________
| function customError($errno, $errstr) { echo "Error: [$errno] $errstr "; echo "Ending Script"; die(); } ___________________________________________________________________ |
The code above is a simple error handling function. When it is triggered, it gets the error level and an error message. It then outputs the error level and message and terminates the script.
Now that we have created an error handling function we need to decide when it should be triggered.
Set Error Handler
The default error handler for PHP is the built in error handler. We are going to make the function above the default error handler for the duration of the script.
It is possible to change the error handler to apply for only some errors, that way the script can handle different errors in different ways. However, in this example we are going to use our custom error handler for all errors:
____________________________________________________________________| set_error_handler("customError"); ___________________________________________________________________ |
Since we want our custom function to handle all errors, the set_error_handler() only needed one parameter, a second parameter could be added to specify an error level.
Example
Testing the error handler by trying to output variable that does not exist:
___________________________________________________________________
| //error handler function function customError($errno, $errstr) { echo "Error: [$errno] $errstr"; } //set error handler set_error_handler("customError"); //trigger error echo($test); ?> ___________________________________________________________________ |
The output of the code above should be something like this:
___________________________________________________________________
| Error: [8] Undefined variable: test ___________________________________________________________________ |
Trigger an Error
In a script where users can input data it is useful to trigger errors when an illegal input occurs. In PHP, this is done by the trigger_error() function.
Example
In this example an error occurs if the "test" variable is bigger than "1":
___________________________________________________________________
| $test=2; if ($test>1) { trigger_error("Value must be 1 or below"); } ?> ___________________________________________________________________ |
The output of the code above should be something like this:
___________________________________________________________________
| Notice: Value must be 1 or below in C:\webfolder\test.php on line 6 _____________________________________________________________ |
An error can be triggered anywhere you wish in a script, and by adding a second parameter, you can specify what error level is triggered.
Possible error types:
- E_USER_ERROR - Fatal user-generated run-time error. Errors that can not be recovered from. Execution of the script is halted
- E_USER_WARNING - Non-fatal user-generated run-time warning. Execution of the script is not halted
- E_USER_NOTICE - Default. User-generated run-time notice. The script found something that might be an error, but could also happen when running a script normally
Example
In this example an E_USER_WARNING occurs if the "test" variable is bigger than "1". If an E_USER_WARNING occurs we will use our custom error handler and end the script:
____________________________________________________________________
| //error handler function function customError($errno, $errstr) { echo "Error: [$errno] $errstr "; echo "Ending Script"; die(); } //set error handler set_error_handler("customError",E_USER_WARNING); //trigger error $test=2; if ($test>1) { trigger_error("Value must be 1 or below",E_USER_WARNING); } ?> ____________________________________________________________________ |
The output of the code above should be something like this:
____________________________________________________________________
| Error: [512] Value must be 1 or below Ending Script ____________________________________________________________________ |
Now that we have learned to create our own errors and how to trigger them, lets take a look at error logging.
Error Logging
By default, PHP sends an error log to the servers logging system or a file, depending on how the error_log configuration is set in the php.ini file. By using the error_log() function you can send error logs to a specified file or a remote destination.
Sending errors messages to yourself by e-mail can be a good way of getting notified of specific errors.
Send an Error Message by E-Mail
In the example below we will send an e-mail with an error message and end the script, if a specific error occurs:
___________________________________________________________________
| //error handler function function customError($errno, $errstr) { echo "Error: [$errno] $errstr "; echo "Webmaster has been notified"; error_log("Error: [$errno] $errstr",1, "someone@example.com","From: webmaster@example.com"); } //set error handler set_error_handler("customError",E_USER_WARNING); //trigger error $test=2; if ($test>1) { trigger_error("Value must be 1 or below",E_USER_WARNING); } ?> __________________________________________________________________ |
The output of the code above should be something like this:
__________________________________________________________________
| Error: [512] Value must be 1 or below Webmaster has been notified __________________________________________________________________ |
And the mail received from the code above looks like this:
__________________________________________________________________
| Error: [512] Value must be 1 or below __________________________________________________________________ |
This should not be used with all errors. Regular errors should be logged on the server using the default PHP logging system.