function in php

Php function -: Like any other language function are same to other function.The real power comes its from php function. Php has more then 1000 function. A function is a small code which takes one more input in the form  of parameter and does some processing and return a value.

In other words we can say that A function is a block of statements that can be used repeatedly in a program.A function will not execute immediately when a page loads.A function will be executed by a call to the function.

There are two main part of function.

  1. Creating a php function
  2. Call a function in php

How to create a function in php -: php provide the facility for user define function.We can create user define function in php. A user define function is start with the word function”.

For example of user define function in php-

<html>

  <head>
       <title>PHP Function</title>
  </head>

<body>

  <?php
    function netnic() {
    echo "welcome in this website";
}

    netnic();

  ?>

 </body>
</html>

The result of this program

welcome in this website

Php function with parameter -: php provide this facility to pass your parameter inside a function.This parameter works as like a variable in the program. for example

 

<html>

 <head>
 <title>Writing PHP Function which returns value</title>
 </head>

<body>
  <?php

   function netnic($num1, $num2, $num3) {

   $total = $num1 + $num2 + $num3;

   echo "Sum of the three numbers is : $total"; }

   netnic(20, 40, 70);

?>
</body>
</html>
   

Output of this program

Sum of the three numbers is : 130

Passing arguments in php -: In the php a information can be passed by  function arguments.A reference to the variable is manipulated by the function rather than a copy of the variable’s value. You can pass an argument by reference by adding an ampersand to the variable name in either the function call or the function definition. For example

<html>

 <head>
 <title>passing arguments with return value</title>
 </head>

<body>
<?php

   function addFive($num) {
   $num += 5;
   }

   function addSix(&$num) {
   $num += 6;
   }

   $netnic = 10;
   addFive( $netnic );

   echo "Original Value is $netnic<br />";

   addSix( $netnic );
   echo "Original Value is $netnic<br />";
?>
</body>
</html>

Output of this program

Original Value is 10
Original Value is 16

 

Returning function value in php-: A function has a return value with return statement .You can return value one or more then using the array in php. For example

<?php
         function netnic($num1, $num2, $num3) {
            $total = $num1 + $num2 + $num3;
            return $total;
         }
         $return_value = netnic(10, 20, 30);
         
         echo "Returned value from the function : $return_value";
      ?>

The output of this program

Returned value from the function : 60

Function parameter set default value -: You can set a parameter to have a default value if the function that the value of function could not  pass. For example

  <?php
         function netnic($param = NULL) {
            print $param;
         }
         
         netnic("This is testing ");
         netnic();
      ?>

Output of this program

This is testing

 

How to call dynamic function in php-Some time that  possible to assign function names as strings to variables and then behavior of  these variables exactly as you would the function name itself.For like this example

      <?php
         function netnic() {
            echo "Hello mr vikram singh <br />";
         }
         
         $function_holder = "netnic";
         $function_holder();
      ?>

The output of this program

Hello mr vikram singh 

 

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