In PHP there are some sorting function .These function are used to sort the array.

sort() : 

This function is used to sort in ascending alphabetical order.

<?php
$mobile = array("Samsung", "Nokia", "Micromax");
sort($mobile);
$length = count($mobile);
for($a = 0; $a < $length; $a++) {

    echo $mobile[$a];
    echo "<br>";
}
?>

<?php
$mobile = array("Samsung", "Nokia", "Micromax");
rsort($mobile);
$length = count($mobile);
for($a = 0; $a < $length; $a++) {

    echo $mobile[$a];
    echo "<br>";
}
?>

<?php
$salary = array("Neha"=>"35000", "Shikha"=>"45000", "Ravi"=>"40000");
asort($salary);

foreach($salary as $a => $a_value) {
    echo "Key=" . $a . ", Value=" . $a_value;
    echo "<br>";
}

?>

<?php
$salary = array("Shikha"=>"45000", "Neha"=>"35000", "Ravi"=>"40000");
ksort($salary);

foreach($salary as $a => $a_value) {
    echo "Key=" . $a . ", Value=" . $a_value;
    echo "<br>";
}

?>

<?php
$salary = array("Shikha"=>"45000", "Neha"=>"35000", "Ravi"=>"40000");
arsort($salary);

foreach($salary as $a => $a_value) {
    echo "Key=" . $a . ", Value=" . $a_value;
    echo "<br>";
}
?>

<?php
$salary = array("Shikha"=>"45000", "Neha"=>"35000", "Ravi"=>"40000");
krsort($salary);

foreach($salary as $a => $a_value) {
    echo "Key=" . $a . ", Value=" . $a_value;
    echo "<br>";
}

?>