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PHP Functions & Type Declarations

PHP functions use the function keyword. Parameter and return type declarations can document and enforce the values a function accepts and returns.

Syntax

function add(int $left, int $right): int {
  return $left + $right;
}

Examples

A typed function

A small, runnable example of this syntax.

<?php
function add(int $left, int $right): int {
  return $left + $right;
}

echo add(2, 3);
?>

Best practices

  • Use scalar and object type declarations at boundaries where they make a function contract clearer.
  • Keep examples small while learning, then combine the idea with a real project.

At a glance

Purpose
Server-side web applications
File extension
.php
Runs in
PHP runtime on a server or CLI
Usually used with
HTML, databases and web servers

Specifications & further reading

Related PHP documentation

PHP function definitions
PHP reference for php function definitions.PHP union types
PHP reference for php union types.PHP default parameters
PHP reference for php default parameters.PHP named arguments
PHP reference for php named arguments.