PHP Functions
User-Defined Functions
A user-defined function in PHP is a function that you can create to perform specific tasks. This allows you to reuse code and organize your program in a modular way.
Syntax for Defining a Function:
function functionName($parameter1, $parameter2, ...) {
// Code to be executed
return $result; // Optional return statement
}
- function: The keyword used to define a function.
- functionName: The name of the function (should be meaningful and follow naming conventions).
- $parameter1, $parameter2: Optional parameters passed to the function.
- {}: The block of code that defines what the function will do.
Example 1: Basic Function without Parameters
<?php
// Define a simple function to print a greeting
function greet() {
echo "Hello, welcome to PHP!<br>";
}
// Call the function
greet(); // Output: Hello, welcome to PHP!
?>
Example 2: Function with Parameters
<?php
// Define a function that takes parameters
function addNumbers($a, $b) {
$sum = $a + $b;
return $sum; // Return the sum
}
// Call the function with arguments
$result = addNumbers(5, 10);
echo "The sum is: " . $result; // Output: The sum is: 15
?>
Example 3: Function with Default Parameters
<?php
// Function with default parameters
function greetUser($name = "Guest") {
echo "Hello, " . $name . "!<br>";
}
// Call the function with no arguments (uses default)
greetUser(); // Output: Hello, Guest!
// Call the function with an argument
greetUser("Alice"); // Output: Hello, Alice!
?>
Basic Variable Function
<?php
// Define two functions
function greet() {
echo "Hello, welcome to PHP!<br>";
}
function farewell() {
echo "Goodbye, have a nice day!<br>";
}
// Variable function to call greet
$functionToCall = 'greet';
$functionToCall(); // Output: Hello, welcome to PHP!
// Variable function to call farewell
$functionToCall = 'farewell';
$functionToCall(); // Output: Goodbye, have a nice day!
?>
Variable Length Argument Functions
func_num_args: This function returns the number of arguments passed to the current function.
<?php
function printArguments() {
$arg1 = func_get_arg(0); // 0 is the index for the first argument
echo "First argument: $arg1<br>";
$arg2 = func_get_arg(1); // 1 is the index for the second argument
echo "Second argument: $arg2<br>";
}
printArguments("Apple", "Banana");
// Output:
// First argument: Apple
// Second argument: Banana
?>
func_get_args: Retrieves all arguments passed to the function and returns them as an array.
<?php
function printAllArguments() {
$args = func_get_args();
foreach ($args as $arg) {
echo "Argument: $arg<br>";
}
}
printAllArguments("Apple", "Banana", "Cherry");
// Output:
// Argument: Apple
// Argument: Banana
// Argument: Cherry
?>
Tags:
php