PHP array_key_exists() function

The array_key_exists () function in PHP is used to check whether the specified key exists in the array or not. It returns a Boolean value TRUE if the given key exists else it returns FALSE.

Syntax

array_key_exists(mixed key,array$array)

Parameter

key(required)- This parameter signifies the value to check.

array(required)- This parameter signifies the input array to check.

Return

This function returns a Boolean value TRUE on success or FALSE on failure.

Example 1

 'first', 2=>'second',3 => 'third',4=>'fourth');
 // passing the key value
 $key= 3;
 // will check whether the key exists or not
 if (array_key_exists($key, $search_array)) {
     echo "The 3 key element is present in the array";
 }
 ?> 

Output

The 2 key element is present in the array

Example 2

'first', 2=>'second',3 => null, 4=>'fourth');
// passing the key value
$key= 3;
// will check whether the key exists or not
if (array_key_exists($key, $search_array)) {
    echo "The ".$key." key element is present in the array";
}
else {
    echo "The ".$key." key element is not present in the array";
}
?> 

Output

The 3 key element is present in the array

Example 3

Output

The 3 key element is not present in the array