What is the purpose of the in_array function in PHP?

The in_array function is used to search for a specific value in an array and return the result. Its purpose is to determine if a value exists in the array. If it exists, it returns true; otherwise, it returns false. The syntax of this function is as follows:

bool in_array ( mixed $needle , array $haystack [, bool $strict = FALSE ] )

In this case, $needle represents the value to search for, $haystack represents the array to search in, and $strict indicates whether to use strict comparison mode (default is false, meaning not using strict mode). For example, the following code demonstrates the use of the in_array function:

$fruits = array("apple", "banana", "orange");
if (in_array("banana", $fruits)) {
    echo "Found banana in the array.";
} else {
    echo "banana not found in the array.";
}

In the example above, the in_array function is called to determine if banana exists in the $fruits array. Since banana is in the array, it will output “Found banana in the array.”