Various PHP tricks: - Array - Find previous array element

php-tricks.php

<?php

/**
 * Array: Find previous element (method 1)
 * @source http://stackoverflow.com/questions/4792673/php-get-previous-array-element-knowing-current-array-key
 */
$array = array(
		12 => array('a','b'),
		34 => array('c','d'),
		56 => array('e','f')
	);

$keys = array_keys($array);
$keyPos = array_flip($keys);
$values = array_values($array);

$search = 56;

echo $values[$keyPos[$search]-1]; // returns previous element's value: array('c','d')
echo $keys[$keyPos[$serach]-1]; // returns previous element's key: 34

/**
 * Array: Find previous element (method 2)
 * @source http://stackoverflow.com/questions/4792673/php-get-previous-array-element-knowing-current-array-key
 */
$array = array(
		12 => array('a','b'),
		34 => array('c','d'),
		56 => array('e','f')
	);
while(key($array) !== null && key($array) !== $key);

echo prev($array); // returns previous element's value: array('c','d')
echo key($array); // returns previous element's key: 34