In the previous post, we discussed the loop in php & form handling in php. In this article we will talk about function in php. 

A function is a piece of code which takes input in the form of parameter and process these parameter and returns a value .A function is  a block of statement that can be used anywhere in the program. PHP has more than 1000 built-in function like fopen(), fclose(),fread(),etc.

PHP gives you option to create your own function. These types of function are called user-defined functions.

User defined functions

It consists of two parts:-

•   Creating a PHP function

•   Calling a PHP function

Creating a function:

Creating your own PHP function is very easy. In the below example we will create a function named Myfunction().The opening braces ‘{‘ indicates the start of the function and closing braces ‘}’ indicates the end of the function.

<?php

//creating a php function

function Myfunction()   // Myfunction is the name of the function(user defined).
{
  echo("This is my First Function.");

}
  Myfunction();  //calling the  Myfunction.

?>

<?php
function StudentName($student) //$student is the argument. It is a variable.
{
    echo "$student is a student of class 9.<br>";
}
StudentName("Ram");
StudentName("Neha");
StudentName("Kirti");
StudentName("Medha");
StudentName("Anshika");
?>

Ram is a student of class 9.
Neha is a student of class 9.
Kirti is a student of class 9.
Medha is a student of class 9.
Anshika is a student of class 9.

<?php

function student($name = "Ram") {
    echo "The student name is : $name <br>";
}

student("shyam");
student(); // will use the default value of Ram
student("Neha");
student("Jagmeet");

?>

The student name is : shyam 
The student name is : Ram //Default value
The student name is : Neha
The student name is : Jagmeet 

<?php
function add($a, $b) {

    $c = $a + $b;
    return $c;

}

echo "50 + 100 = " . add(50, 100) . "<br>";
echo "70 + 130 = " . add(70, 130) . "<br>";
echo "20 + 40 = " . add(20, 40);
?>

50 + 100 = 150
70 + 130 = 200
20 + 40 = 60