PHP Functions PHP
- PHP Tutorial
- What is PHP
- Install PHP
- PHP Example
- PHP Echo
- PHP Print
- PHP Variables
- PHP $ and $$ Variables
- PHP Constants
- Magic Constants
- PHP Data Types
- PHP Operators
- PHP Comments
- PHP Boolean
- PHP is_bool() function
- PHP Integer
- PHP is_int() function
- PHP Float
- PHP is_float Function
- PHP Compound Types
- PHP Special Types
- PHP is_null() function
- PHP If Else
- PHP Switch
- PHP For Loop
- PHP While Loop
- PHP do while loop
- PHP Break
- PHP Functions
- PHP Parameterized Function
- PHP Call By Value
- PHP Call By Reference
- PHP Default Argument Values Function
- PHP Variable Length Argument Function
- PHP Recursive Function
- PHP Arrays
- PHP Indexed Array
- PHP Associative Array
- PHP Multidimensional Array
- PHP Array Functions
- PHP String
- PHP String Functions
- PHP Math functions
- PHP Form Handling | GET and POST method
- PHP Include File
- PHP Cookie
- PHP Session
- PHP File Handling
- PHP Open File
- PHP Read File
- PHP Write File
- PHP Append to File
- PHP Delete File
- PHP File Upload
- PHP Download File
- PHP Mail
- PHP MySQL Connect
- PHP MySQL Create Database
- PHP MySQL Create Table Example
- PHP MySQL Insert Record
- PHP Prepared Statements
- PHP MySQL Update Record
- PHP MySQL Delete Record
- PHP MySQL Select
- PHP MySQL Order By
- PHP Limit Data MySql
- PHP JSON
- PHP XML Parsers
- PHP SimpleXML Parser
- PHP SimpleXML - Get Node/Attribute Values
- PHP XML Expat Parser
- PHP XML DOM Parser
- PHP - AJAX intro
- MySQL CREATE VIEW
PHP Functions
PHP Functions
PHP function is a piece of code that can be reused many times. It can take input as argument list and return value. There are thousands of built-in functions in PHP.
In PHP, we can define Conditional function, Function within Function and Recursive function also.
Advantage of PHP Functions
Code Reusability: PHP functions are defined only once and can be invoked many times, like in other programming languages.
Less Code: It saves a lot of code because you don't need to write the logic many times. By the use of function, you can write the logic only once and reuse it.
Easy to understand: PHP functions separate the programming logic. So it is easier to understand the flow of the application because every logic is divided in the form of functions.
PHP User-defined Functions
We can declare and call user-defined functions easily. Let's see the syntax to declare user-defined functions.
Syntax
- function functionname(){
- //code to be executed
- }
PHP Functions Example
File: function1.php
- <?php
- function sayHello(){
- echo "Hello PHP Function";
- }
- sayHello();//calling function
- ?>
Output:
PHP Function Arguments
We can pass the information in PHP function through arguments which is separated by comma.
PHP supports Call by Value (default), Call by Reference, Default argument values and Variable-length argument list.
Let's see the example to pass single argument in PHP function.
File: functionarg.php
- <?php
- function sayHello($name){
- echo "Hello $name<br/>";
- }
- sayHello("Sonoo");
- sayHello("Vimal");
- sayHello("John");
- ?>
Output:
Hello Vimal
Hello John
Let's see the example to pass two argument in PHP function.
File: functionarg2.php
- <?php
- function sayHello($name,$age){
- echo "Hello $name, you are $age years old<br/>";
- }
- sayHello("Sonoo",27);
- sayHello("Vimal",29);
- sayHello("John",23);
- ?>
Output:
Hello Vimal, you are 29 years old
Hello John, you are 23 years old
PHP Call By Reference
Value passed to the function doesn't modify the actual value by default (call by value). But we can do so by passing value as a reference.
By default, value passed to the function is call by value. To pass value as a reference, you need to use ampersand (&) symbol before the argument name.
Let's see a simple example of call by reference in PHP.
File: functionref.php
- <?php
- function adder(&$str2)
- {
- $str2 .= 'Call By Reference';
- }
- $str = 'Hello ';
- adder($str);
- echo $str;
- ?>
Output:
PHP Function: Default Argument Value
We can specify a default argument value in function. While calling PHP function if you don't specify any argument, it will take the default argument. Let's see a simple example of using default argument value in PHP function.
File: functiondefaultarg.php
- <?php
- function sayHello($name="Sonoo"){
- echo "Hello $name<br/>";
- }
- sayHello("Rajesh");
- sayHello();//passing no value
- sayHello("John");
- ?>
Output:
Hello Sonoo
Hello John
PHP Function: Returning Value
Let's see an example of PHP function that returns value.
File: functiondefaultarg.php
- <?php
- function cube($n){
- return $n*$n*$n;
- }
- echo "Cube of 3 is: ".cube(3);
- ?>
Output: