How Can I Effectively Use `in_array()` to Search Multidimensional Arrays in PHP?

Interrogating Multidimensional Arrays with in_array()

In_array() effortlessly identifies the presence of elements within a one-dimensional array. However, its application to multidimensional arrays presents a challenge, rendering its utility questionable. To address this issue, a recursive function can be employed to recursively traverse the multidimensional array and ascertain the presence of the desired element.

The function, aptly named in_array_r(), takes three parameters: the target element ($needle), the array to be searched ($haystack), and an optional parameter ($strict) that dictates whether strict equality (===) or relaxed equality (==) should be utilized in the comparison.

The function's iterative process involves examining each element ($item) in the haystack. If the item matches the target element with respect to the specified comparison method, the function returns true. If the element is itself an array, the function recursively invokes itself with that array as the new haystack, effectively exploring further levels of the multidimensional structure.

The recursion continues until all elements have been inspected or until the target element is discovered. Should the element remain elusive, the function returns false.

To demonstrate its functionality, consider the following usage:

$b = array(array("Mac", "NT"), array("Irix", "Linux"));
echo in_array_r("Irix", $b) ? 'found' : 'not found';

In this example, the function searches for the presence of "Irix" in the multidimensional array $b. If found, it outputs "found"; otherwise, it outputs "not found."

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