PHP reference

empty

Checks that a variable does not exist or holds an "empty" value.

Syntax

empty(mixed $var): bool

Parameter	Type	Description
$var	mixed	The variable to check.

bool`true` for a missing variable, `null`, `false`, `0`, `'0'`, an empty string and an empty array.

Empty values:

<?php
 
var_dump(empty(''));
var_dump(empty([]));
var_dump(empty('text'));

Output:

bool(true)
bool(true)
bool(false)

A trap: the string "0" counts as empty too:

<?php
 
$quantity = '0';
 
var_dump(empty($quantity));
var_dump($quantity === '');

Output:

bool(true)
bool(false)

If zero is a valid value, check more precisely: $value === '' or $value === null.

Variables — How to declare variables in PHP, name them and interpolate them into strings.