in_array() and multidimensional array

Question

I use in_array() to check whether a value exists in an array like below,

$a = array(\"Mac\", \"NT\", \"Irix\", \"Linux\");
if (in_array(\"Irix\"         


        

Answer 1

The accepted solution (at the time of writing) by jwueller

function in_array_r($needle, $haystack, $strict = false) {
    foreach ($haystack as $item) {
        if (($strict ? $item === $needle : $item == $needle) || (is_array($item) && in_array_r($needle, $item, $strict))) {
            return true;
        }
    }

    return false;
}

Is perfectly correct but may have unintended behaviuor when doing weak comparison (the parameter $strict = false).

Due to PHP's type juggling when comparing values of different type both

"example" == 0

and

0 == "example"

Evaluates true because "example" is casted to int and turned into 0.

(See Why does PHP consider 0 to be equal to a string?)

If this is not the desired behaviuor it can be convenient to cast numeric values to string before doing a non-strict comparison:

function in_array_r($needle, $haystack, $strict = false) {
    foreach ($haystack as $item) {

        if( ! $strict && is_string( $needle ) && ( is_float( $item ) || is_int( $item ) ) ) {
            $item = (string)$item;
        }

        if (($strict ? $item === $needle : $item == $needle) || (is_array($item) && in_array_r($needle, $item, $strict))) {
            return true;
        }
    }

    return false;
}