PHP Functions

A Function is a peace of code of large program.

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 types of Functions

  • User Defined Functions
  • In-Built Functions

    • User Defined Functions

    Besides the built-in PHP functions, we can create our own functions.

    Create a User Defined Function in PHP

    A user defined function declaration starts with the word "function":

    Syntax

    function functionName() {
    code to be executed;
    }


    Note:
  • A function name can start with a letter or underscore (not a number).

    • Give the function a name that reflects what the function does!

    Function names are NOT case-sensitive.

    In the example below, we create a function named "writeMsg()". The function outputs "Hello world!". To call the function, just write its name:

    Example

    Return "world" from the string:

    <?php
    function writeMsg() {
        echo "Hello world!";
    }

    writeMsg(); // call the function
    ?>

    Run Example>>



    PHP Function Arguments

    Information can be passed to functions through arguments. An argument is just like a variable.

    Arguments are specified after the function name, inside the parentheses. You can add as many arguments as you want, just separate them with a comma.

    The following example has a function with one argument ($fname). When the familyName() function is called, we also pass along a name (e.g. Jani), and the name is used inside the function, which outputs several different first names, but an equal last name:

    Example

    Using the start parameter with different positive and negative numbers:

    <?php
    function familyName($fname) {
        echo "$fname Thakor.<br>";
    }

    familyName("Bharatsinh");
    familyName("Falguni");
    familyName("Keyur");
    familyName("Alkesh");
    familyName("Ankita");
    ?>

    Run Example>>

    PHP Default Argument Value

    The following example shows how to use a default parameter. If we call the function setHeight() without arguments it takes the default value as argument:

    Example

    Using the start parameter with different positive and negative numbers:

    <?php
    function setHeight($minheight = 50) {
        echo "The height is : $minheight <br>";
    }

    setHeight(350);
    setHeight(); // will use the default value of 50
    setHeight(135);
    setHeight(80);
    ?>

    Run Example>>

    PHP Functions - Returning values

    To let a function return a value, use the return statement:

    Example

    Using the start parameter with different positive and negative numbers:

    <<?php
    function sum($x, $y) {
        $z = $x + $y;
        return $z;
    }

    echo "5 + 10 = " . sum(5, 10) . "<br>";
    echo "7 + 13 = " . sum(7, 13) . "<br>";
    echo "2 + 4 = " . sum(2, 4);
    ?>

    Run Example>>