Check if a value exists in an array/object.

search_for_value.php

<?php
/**
 *  Check if an array is a multidimensional array.
 *
 *  @param   array   $arr  The array to check
 *  @return  boolean       Whether the the array is a multidimensional array or not
 */
function is_multi_array( $x ) {
    if( count( array_filter( $x,'is_array' ) ) > 0 ) return true;
    return false;
}

/**
 *  Convert an object to an array.
 *
 *  @param   array   $object  The object to convert
 *  @return  array            The converted array
 */
function object_to_array( $object ) {
    if( !is_object( $object ) && !is_array( $object ) ) return $object;
    return array_map( 'object_to_array', (array) $object );
}

/**
 *  Check if a value exists in the array/object.
 *
 *  @param   mixed    $needle    The value that you are searching for
 *  @param   mixed    $haystack  The array/object to search
 *  @param   boolean  $strict    Whether to use strict search or not
 *  @return  boolean             Whether the value was found or not
 */
function search_for_value( $needle, $haystack, $strict=true ) {
    $haystack = object_to_array( $haystack );

    if( is_array( $haystack ) ) {
        if( is_multi_array( $haystack ) ) {   // Multidimensional array
            foreach( $haystack as $subhaystack ) {
                if( search_for_value( $needle, $subhaystack, $strict ) ) {
                    return true;
                }
            }
        } elseif( array_keys( $haystack ) !== range( 0, count( $haystack ) - 1 ) ) {    // Associative array
            foreach( $haystack as $key => $val ) {
                if( $needle == $val && !$strict ) {
                    return true;
                } elseif( $needle === $val && $strict ) {
                    return true;
                }
            }

            return false;
        } else {    // Normal array
            if( $needle == $haystack && !$strict ) {
                return true;
            } elseif( $needle === $haystack && $strict ) {
                return true;
            }
        }
    }

    return false;
}