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PHP Functionsphp function

PHP functions help us write clean, reusable code by grouping logic into blocks. PHP has many built-in functions, and we can also create our own.

What is a Function in PHP?

A function is a named block of code that runs only when we call it. Functions help us avoid repeating code again and again.

  • Functions can take arguments (input values)

  • They can return a result

  • They are not case-sensitive

Built-in vs User-defined Functions

Built-in Functions

PHP provides 1000+ built-in functions for various tasks like string handling, array processing, date formatting, etc.

Example:

echo strlen("Hello");  // Output: 5

User-defined Functions

You can create your own functions to solve specific problems in your program.

Creating a User-defined Function

Use the function keyword to define a function.

Syntax:

function functionName() {
    // code to run
}

Example:

function greet() {
    echo "Hello, world!";
}
greet();

Output:
Hello, world!

PHP Function with Parameters

You can pass data to a function using parameters.

Example:

function showName($name) {
    echo "Welcome, $name!<br>";
}
showName("Amit");
showName("Priya");

Output:
Welcome, Amit!
Welcome, Priya!

Function with Multiple Parameters

You can also pass more than one parameter.

Example:

function studentDetails($name, $year) {
    echo "$name joined in $year<br>";
}
studentDetails("Raj", 2022);
studentDetails("Neha", 2023);

Output:
Raj joined in 2022
Neha joined in 2023

Default Argument Value

If a parameter is not passed, PHP can use a default value.

Example:

function setHeight($minHeight = 100) {
    echo "Minimum height: $minHeight<br>";
}
setHeight(150);
setHeight();

Output:
Minimum height: 150
Minimum height: 100

Returning Values from a Function

Use return to send back a result from a function.

Example:

function add($a, $b) {
    return $a + $b;
}
echo add(4, 5);

Output:
9

Pass by Value vs Pass by Reference

By default, PHP passes arguments by value (a copy). But you can use & to pass by reference.

Example (by value):

function update($x) {
    $x += 10;
}
$a = 5;
update($a);
echo $a;  // Output: 5

Example (by reference):

function update(& $x) {
    $x += 10;
}
$a = 5;
update($a);
echo $a;  // Output: 15

Best Practices for PHP Functions

  • Use clear and meaningful names

  • Avoid too many parameters

  • Keep functions short and focused

  • Always return a value if needed

Real-world Example

Example: A function to calculate total price including GST

function getTotalPrice($amount, $gst = 18) {
    return $amount + ($amount * $gst / 100);
}
echo getTotalPrice(1000);  // Output: 1180

Conclusion

PHP functions help make your code simple, reusable, and maintainable. You can use both built-in and user-defined functions to manage logic and reduce repetition.