排序数组（“1:40”，“2:30”，“6:33”）从最低到最高？

Question

I am new in PHP I have an array a different format but, I don't know how to sort from lowest to highest i know the inbuilt function like sort and others too but these are not suitable for me please help if anybody knows, I have this array format

$array = array("2:90","8:49","3:77","4:98");

and this array needs to sort as

8:49,3:77,2:90,4:98

sort by right values after symbol (:)

Answer 1

You could define a custom comparator and use usort with it:

<?php

function cmp($a, $b) {
    // Split the value by the ":" delimiter and store each side into variable
    list($a_first, $a_second) = explode(':', $a);
    list($b_first, $b_second) = explode(':', $b);
    // If the second substrings are not equal compare them
    if ($a_second != $b_second) {
      return strcmp($a_second, $b_second);
    }
    // If they are equal compare the values in the first substrings
    return strcmp($a_first, $b_first);
}

$array = array("2:90","1:90","8:49","3:77","4:98");
print "Before sorting:\n";
print_r($array);
usort($array, "cmp");
print "After sorting:\n";
print_r($array);

?>

Output:

Before sorting: 
Array
(
    [0] => 2:90
    [1] => 1:90
    [2] => 8:49
    [3] => 3:77
    [4] => 4:98
)
After sorting: 
Array
(
    [0] => 8:49
    [1] => 3:77
    [2] => 1:90
    [3] => 2:90
    [4] => 4:98
)

Explanations and links to docs of other functions used:

• explode - Split a string by a string.
• strcmp - Binary safe string comparison.

---

A solution to the additional requirement to handle decimals provided in comments of this answer:

<?php

function cmp($a, $b) {
    // Split the value by the ":" delimiter and store each side into variable
    list($a_first, $a_second) = array_map('floatval', explode(':', $a));
    list($b_first, $b_second) = array_map('floatval', explode(':', $b));
    // If the second substrings are not equal compare them
    if (abs($a_second - $b_second) >= PHP_FLOAT_EPSILON) {
      return $a_second - $b_second;
    }
    // If they are equal compare the values in the first substrings
    return $a_first - $b_first;
}

$array = array("2:90.60","2:95.67","1:95.67","8:49","3:77.66","4:98.30");
print "Before sorting:\n";
print_r($array);
usort($array, "cmp");
print "After sorting:\n";
print_r($array);

?> 

Output:

Before sorting:
Array
(
    [0] => 2:90.60
    [1] => 2:95.67
    [2] => 1:95.67
    [3] => 8:49
    [4] => 3:77.66
    [5] => 4:98.30
)
After sorting:
Array
(
    [0] => 8:49
    [1] => 3:77.66
    [2] => 2:90.60
    [3] => 1:95.67
    [4] => 2:95.67
    [5] => 4:98.30
)

Explanations and links to docs of other functions used:

• array_map - Applies the callback to the elements of the given arrays
• floatval - Get float value of a variable