In this article Functions in PHP we give the information about functions are an important part of programming in PHP. This makes code reusable and keeps the program organized and modular.
Functions in PHP
Function is a code block which is given a name. It can be used again and again. Whenever a function is called, it executes the work.
How to create a function in PHP?
Syntax of creating a function
function functionName(parameters) {
// code block
}
Calling a Function
functionName(arguments);
Types of Function
- Built-in Functions: Functions already available in PHP.
Like: strlen(), strpos(), array_push().
- User-defined Functions: Functions created by the user.
User-defined Functions (Examples)
Example 1: Function without parameters
<?php
function greet() {
echo “Hello, this is an example of a PHP Function!<br>”;
}
// call the function
greet();
?>
Output:
Hello, this is an example of PHP Function!
Example 2: Function with parameters
<?php
function greetUser($name) {
echo “Hello, $name!<br>”;
}
// call the function
greetUser(“Rahul”);
greetUser(“Sonia”);
?>
Output:
Hello, Rahul!
Hello, Sonia!
Example 3: Function with Return Value
<?php
function addNumbers($a, $b) {
return $a + $b;
?>
// Call the function and print the result
$result = addNumbers(10, 20);
echo “Addition result: $result<br>”;
?>
Output:
Result of addition: 30
Example 4: Default Parameters
<?php
function greet($name = “Guest”) {
echo “Hello, $name!<br>”;
}
//use default value
greet();
greet(“Ravi”);
?>
Output:
Hello, guest!
Hello, Ravi!
Arguments and Parameters in Function
- Pass by Value:
By default, arguments are passed by value in PHP.
<?php
function changeValue($num) {
$num += 10;
echo “Inside: $num<br>”;
}
$value = 20;
changeValue($value);
echo “Outside: $value<br>”;
?>
Output:
Inside: 30
Out: 20
- Pass by Reference:
If you want to pass a reference to a variable, use &.
<?php
function changeValue(&$num) {
$num += 10;
echo “Inside: $num<br>”;
}
$value = 20;
changeValue($value);
echo “Outside: $value<br>”;
?>
Output:
Inside: 30
Out: 30
Variable Functions
In PHP, you can call a variable like a function.
<?php
function sayHello() {
echo “Hello World!<br>”;
}
$func = “sayHello”;
$func(); // call variable function
?>
Output:
Hello World!
Anonymous Functions (Lambda Functions)
In PHP you can create functions without names.
<?php
$greet = function($name) {
return “Hello, $name!”;
}
echo $greet(“Ajay”);
?>
Output:
Hello, Ajay!
Arrow Functions (available since PHP 7.4)
Arrow Functions are used for small code blocks.
<?php
$multiply = fn($a, $b) => $a * $b;
echo $multiply(5, 6); //30
?>
Recursive Functions (functions that call themselves)
Example: Using Factorial
<?php
function factorial($n) {
if ($n <= 1) {
return 1;
}
return $n * factorial($n – 1);
}
echo “Factorial of 5: ” .factorial(5);
?>
Output:
Factorial of 5: 120
Function Scope (Scope Levels)
- Local Scope:
Variables created inside the function cannot be accessed outside.
<?php
function test() {
$x = 10; // Local Scope
echo $x;
}
test();
// echo $x; // will give error
?>
- Global Scope:
Variables declared outside the function can be accessed using $GLOBALS.
<?php
$x = 10;
function test() {
global $x; // or $GLOBALS[‘x’]
echo $x;
}
test();
?>
-
Static Scope:
Static variables are used to retain values between function calls.
<?php
function counter() {
static $count = 0;
$count++;
echo $count . “<br>”;
}
counter(); //1 counter(); // 2 counter(); //3
?>
Conclusion
- Functions make code reusable.
- Various methods of passing parameters and values are available.
- Built-in, user-defined, and anonymous functions are available in PHP.
- Use functions to create modular and scalable code.
Some More:
POP- Introduction to Programming Using ‘C’
OOP – Object Oriented Programming
DBMS – Database Management System
RDBMS – Relational Database Management System
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