PHP multidimensional array sorting (usort, uasort)_PHP tutorial

//Define multi-dimensional array
$a = array(
array("sky", "blue"),
array("apple", "red"),
array("tree", "green"));
//Customized array comparison function, compare based on the second element of the array.
function my_compare($a, $b) {
if ($a[1] < $b[1])
return -1;
else if ($a[1] = = $b[1])
return 0;
else
return 1;
}
//Sort
usort($a, 'my_compare');
/ /Output results
foreach($a as $elem) {
echo "$elem[0] : $elem[1]
";
}

? >

sky : blue
tree : green
apple : red

$a = array(
'Sunday' => array(0,'7th'),
'Friday' => array(5,'5th'),
'Tuesday'=> array(2,'2nd'));

function my_compare($a, $b) {
if ($a[1] < $b[1])
return -1;
else if ($a[1 ] == $b[1])
return 0;
else
return 1;
}
//Press the second element of the value of the $a array (7th, 5th, 2nd) Sort
uasort($a, 'my_compare');
foreach($a as $key => $value) {
echo "$key : $value[0] $value[ 1]
";
}
//Sort by the second character (r, u, u) of the key of the $a array
uksort($a, 'my_compare ');
foreach($a as $key => $value) {
echo "$key : $value[0] $value[1]
";
}

?>