Pre-requisite: PHP | array_keys() Function
The array_key_exists() is an inbuilt function of PHP and is used to check whether a specific key or index is present inside an array or not. The function returns True if the specified key is found in the array otherwise returns false.
Syntax:
boolean array_key_exists($index, $array)
Parameters: This function takes two arguments and are described below:
- $index (mandatory): This parameter refers to the key that is needed to be searched for in an input array.
- $array (mandatory): This parameter refers to the original array in which we want to search the given key $index.
Return Value: This function returns a boolean value i.e., TRUE and FALSE depending on whether the key is present in the array or not respectively.
Note: Nested keys will return result as FALSE.
Examples:
Input: $array = array("ram"=>25, "krishna"=>10, "aakash"=>20, "gaurav") $index = "aakash" Output : TRUE Input : $array = ("ram", "krishna", "aakash", "gaurav"); $index = 1 Output : TRUE Input : $array = ("ram", "krishna", "aakash", "gaurav"); $index = 4 Output : FALSE
Below programs ilustrates the array_key_exists() function in PHP:
-
In the following program we will see how we can find a key inside an array that holds key_value pair.
<?php
// PHP function to illustrate the use
// of array_key_exists()
function
Exists(
$index
,
$array
)
{
if
(
array_key_exists
(
$index
,
$array
)){
echo
"Found the Key"
;
}
else
{
echo
"Key not Found"
;
}
}
$array
=
array
(
"ram"
=>25,
"krishna"
=>10,
"aakash"
=>20,
"gaurav"
);
$index
=
"aakash"
;
print_r(Exists(
$index
,
$array
));
?>
Output:
Found the Key
-
If no key_value pair exits, as in the below case, then the array takes the default keys i.e. numeric keys starting form zero, into consideration and returns True as far as the $index limit ranges.
<?php
// PHP function to illustrate the use of
// array_key_exists()
function
Exists(
$index
,
$array
)
{
if
(
array_key_exists
(
$index
,
$array
)) {
echo
"Found the Key"
;
}
else
{
echo
"Key not Found"
;
}
}
$array
=
array
(
"ram"
,
"krishna"
,
"aakash"
,
"gaurav"
);
$index
= 2;
print_r(Exists(
$index
,
$array
));
?>
Output:
Found the Key
Reference:
http://php.net/manual/en/function.array-key-exists.php