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PHP functions are similar to other programming languages. A function is a piece of code that takes one more input in the form of parameter and does some processing and returns a value. Functions are blocks of code that perform specific tasks.Built-in functions are functions that are defined with PHP. PHP has more than 1000 built-in functions, and also you can customize functions. In this tutorial we will see how to create the custom function in PHP.
Creating a PHP Function
A user-defined function declaration starts with the word function. A function name must start with a letter or an underscore. Function names are not case-sensitive. Function can take zero or any number of arguments.
A function is defined using following :
<?php
function function_name($arg_1, $arg_2, /* ..., */ $arg_n)
{
/* Function Body */
return $retval;
}
?>
Example :
<?php
function demo() {
echo "Hello world!";
}
?>
In the above example , we create a function named “demo()”. The opening curly brace ” { ” indicates the beginning of the function code, and the closing curly brace “}” indicates the end of the function. The function outputs “Hello world!”.
Calling the Function
To call the function, just write its name followed by brackets ().
<?php
function demo() {
echo "Hello world!";
}
demo(); // call the function
?>
PHP Functions returning value
A function can return a value using the return statement in conjunction with a value or object. return stops the execution of the function and sends the value back to the calling code. You can return more than one value from a function using return array(val1, val2, val3, val4).
<?php
function add($num1, $num2) {
$sum = $num1 + $num2;
return $sum;
}
$addition = add(10, 20);
echo "Returned value from the function : $addition";
?>
Dynamic Function Calls
In PHP we can assign function names as strings to variables and then treat these variables exactly as you would the function name itself.
Example:
<?php
function demo() {
echo "Hello World";
}
$function_name = "demo";
$function_name();
?>