Using PHP array_search to Find Keys in an Array

In PHP development, arrays are a common and useful data structure, and the array_search function can be used to locate the key associated with a specific value.

The basic syntax of the function is:

mixed array_search ( mixed $needle , array $haystack [, bool $strict = false ] )

The three parameters are:

$needle : the value to search for.

$haystack : the array to search in.

$strict (optional): when true , the comparison is type‑strict; the default false compares values without type checking.

Example – finding the key of "apple" in a simple fruit array:

$fruits = array("banana", "apple", "orange", "grape");
$key = array_search("apple", $fruits);
echo "The key for 'apple' is: " . $key;

The output will be:

The key for 'apple' is: 1

If the searched value appears multiple times, array_search returns only the first matching key.

When strict comparison is required, set the third argument to true . The following example shows strict mode with mixed types:

$fruits = array("banana", 1, "2", true);
$key = array_search(1, $fruits, true);
echo "The key for 1 is: " . $key . "\n";
$key = array_search("1", $fruits, true);
echo "The key for '1' is: " . $key;

The output will be:

The key for 1 is: 1
The key for '1' is:

In this strict‑mode example, the numeric 1 and the string '1' are considered different, so the second search returns false (no key).

In summary, array_search provides a convenient way to locate a value’s key in an array; it returns the first match by default, and setting $strict to true enables type‑strict searching.

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