How to check if a variable is an array in PHP?
In this tutorial, we are going to see how to check if a variable is an array in PHP?
is_array()
The function is_array($var) check if the passed variable is an array:
<?php
var_dump( is_array(array()) ); // true
var_dump( is_array(array(1, 2, 3)) ); // true
var_dump( is_array($_SERVER) ); // true
var_dump( is_array(1) ); // false
var_dump( is_array(0) ); // false
var_dump( is_array(2.555) ); // false
var_dump( is_array('lorem') ); // false
var_dump( is_array(true) ); // false
var_dump( is_array(new stdClass()) ); // false
?>
Output:
bool(true) bool(true) bool(true) bool(false) bool(false) bool(false) bool(false) bool(false) bool(false)
The use of is_array() to check function parameters is not absolutely necessary, since arrays can already be specified:
<?php
function myFunction(array $a) {
// ...
}
myFunction('hello'); // generates an error
?>
Output:
Fatal error: Uncaught TypeError: Argument 1 passed to myFunction() must be of the type array, string given, called in [...][...] on line 6 and defined in [...][...]:2
Stack trace:
#0 [...][...](6): myFunction('hello')
#1 {main}
thrown in [...][...] on line 2
Function parameters:
The function is_array() can be useful when a function parameter should usually be an array, but can optionally have other data types. The following example defines a function “searchMultipleUser”, which is called with multiple names or ID numbers – passed as array. But there is also the option to pass only a string (a single user name) or an integer (a single ID). The string or ID is then automatically converted into an array.
<?php
function searchMultipleUser($name) {
if (!is_array($name)) {
// A name was given?
if (!is_string($name) && !is_int($name)) {
throw new Exception('String/integer or array of strings/integers expected.');
} else {
return searchMultipleUser(array($name));
}
} else {
// search
// here, we output the names / IDs
echo("search for: ");
array_walk($name, function($n) { echo "$n, "; });
echo("\n");
}
}
searchMultipleUser('Alex');
searchMultipleUser(10001);
searchMultipleUser(array('Alex', 'Bob', 'Ali'));
?>
Output:
search for: Alex, search for: 10001, search for: Alex, Bob, Ali,
In the next example, a parameter is completely optional, but must be an array if defined by the developer. If it is not passed, it should be automatically filled with an empty array.
<?php
function check(array $data=null) {
// check if $data is an array
if (!is_array($data)) {
// here some default values could be set
$data = array();
}
var_dump($data);
}
check(array(1, 2, 3, 4));
check();
?>
Output:
array(4) {
[0]=>
int(1)
[1]=>
int(2)
[2]=>
int(3)
[3]=>
int(4)
}
array(0) {
}
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