PHP Functions

The real power of PHP comes from its functions. There are more than about 1000 built-in functions available in PHP, which is much enough to perform a lot of task.

PHP5 Functions

You are free to create your own functions (user-defined functions). A function is basically a block of code that can be used to perform some particular task in your program.

Create a Function in PHP

A function in PHP is created with the help of function keyword. Here is the general form to declare a function in PHP:

function functionName()
{
   code to be executed here;
}

Here, function is the keyword used in declaring the function in PHP, functionName is the name of the function. You can give a name to the function starting with a letter or underscore (but not with a number).

PHP Functions Example

Here is an example, creates a function named writeMsg(), to write a message as output:

<!DOCTYPE html>
<html>
<head>
   <title>PHP function Example</title>
</head>
<body>
<?php
   function writeMsg()
   {
      echo "This is PHP function tutorial.";
   }
   writeMsg();
?>
</body>
</html>

Here is the output produced by the above PHP script:

A function with parameters is known as parameterized function in PHP.

Here is another example, uses function with parameters in PHP:

<html>
<head>
   <title>Writing PHP Function with Parameters</title>
</head>
<body>
<?php
   function addFunction($num1, $num2)
   {
      $sum = $num1 + $num2;
      echo "Sum of the passed numbers is : $sum";
   }
   addFunction(100, 200);
?>
</body>
</html>

Here is the output of this PHP script:

Let's take another example also demonstrating functions in PHP with parameter.

<html>
<head>
   <title>Function Example in PHP</title>
</head>
<body>
<?php
   function printTable($num)
   {
      for($i=1;$i<=10;$i++)
      {
         echo $num*$i;
         echo " ";
      }
   }
   printTable(2);
   echo "<br/>";
   printTable(3);
   echo "<br/>";
   printTable(4);
   echo "<br/>";
?>
</body>
</html>

Here is the sample output produced by the above parameterized function in PHP example.