How to implement array sorting in php+

In PHP, sorting is one of the operations we often need to use in daily programming. For sorting arrays, PHP provides a variety of sorting functions to help us complete this task.

Next we will introduce several common PHP array sorting methods.

1. sort function

The sort function is one of PHP's built-in sorting functions. It can sort an array in ascending order or an associative array.

The syntax of the sort function is:

bool sort ( array &$array [, int $sort_flags = SORT_REGULAR ] )

Among them, array is the array to be sorted, sort_flags is an optional parameter, which can be used to specify the sorting method, such as:

• SORT_REGULAR - Default sorting method. Compare each item in the ordinary way.
• SORT_NUMERIC - Compares each item numerically.
• SORT_STRING - Compare each item as a string.
• SORT_LOCALE_STRING - Compare each item as a localized string.
• SORT_NATURAL - Compare each item in its natural order.
• SORT_FLAG_CASE - Only valid when used with SORT_STRING or SORT_NATURAL. Sort in a case-insensitive manner.

Sample code:

$numbers = array(1,3,2,5,4);
sort($numbers);
print_r($numbers);

Output result:

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
)

2. rsort function

rsort function is the reverse order of sort function The sort function can also sort an array in descending order.

The syntax of the rsort function is:

bool rsort ( array &$array [, int $sort_flags = SORT_REGULAR ] )

Among them, array is the array to be sorted, and sort_flags is an optional parameter, indicating the sorting method. The specific meaning is the same as the sort function.

Sample code:

$numbers = array(1,3,2,5,4);
rsort($numbers);
print_r($numbers);

Output result:

Array
(
    [0] => 5
    [1] => 4
    [2] => 3
    [3] => 2
    [4] => 1
)

3. asort function

The asort function can sort an associative array in ascending order. However, the relevance of the original key is retained, that is, the key value will change accordingly.

The syntax of the asort function is:

bool asort ( array &$array [, int $sort_flags = SORT_REGULAR ] )

Among them, array is the array to be sorted, and sort_flags is an optional parameter, indicating the sorting method. The specific meaning is the same as the sort function.

Sample code:

$numbers = array("a"=>1,"c"=>3,"b"=>2,"e"=>5,"d"=>4);
asort($numbers);
print_r($numbers);

Output result:

Array
(
    [a] => 1
    [b] => 2
    [c] => 3
    [d] => 4
    [e] => 5
)

4. arsort function

The arsort function is the reverse sorting function of the asort function. It is also possible to sort an associative array in descending order.

The syntax of the arsort function is:

bool arsort ( array &$array [, int $sort_flags = SORT_REGULAR ] )

Among them, array is the array to be sorted, and sort_flags is an optional parameter, indicating the sorting method. The specific meaning is the same as the sort function.

Sample code:

$numbers = array("a"=>1,"c"=>3,"b"=>2,"e"=>5,"d"=>4);
arsort($numbers);
print_r($numbers);

Output result:

Array
(
    [e] => 5
    [d] => 4
    [c] => 3
    [b] => 2
    [a] => 1
)

5. ksort function

The ksort function can sort an associative array in ascending order. However, the relevance of the original key is retained, that is, the key value will not change accordingly.

The syntax of the ksort function is:

bool ksort ( array &$array [, int $sort_flags = SORT_REGULAR ] )

Among them, array is the array to be sorted, and sort_flags is an optional parameter, indicating the sorting method. The specific meaning is the same as the sort function.

Sample code:

$numbers = array("a"=>1,"c"=>3,"b"=>2,"e"=>5,"d"=>4);
ksort($numbers);
print_r($numbers);

Output result:

Array
(
    [a] => 1
    [b] => 2
    [c] => 3
    [d] => 4
    [e] => 5
)

6. krsort function

The krsort function is the reverse sorting function of the ksort function. It is also possible to sort an associative array in descending order.

The syntax of the krsort function is:

bool krsort ( array &$array [, int $sort_flags = SORT_REGULAR ] )

Among them, array is the array to be sorted, sort_flags is an optional parameter, indicating the sorting method, and the specific meaning is the same as the sort function.

Sample code:

$numbers = array("a"=>1,"c"=>3,"b"=>2,"e"=>5,"d"=>4);
krsort($numbers);
print_r($numbers);

Output result:

Array
(
    [e] => 5
    [d] => 4
    [c] => 3
    [b] => 2
    [a] => 1
)

The above is an introduction to the method of implementing array sorting in PHP. I believe you have mastered the related functions and usage of array sorting. , which can easily meet the sorting needs in daily programming.

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