PHP - Ds Map::ksorted() Function

---

---

The PHP Ds\Map::ksorted() function is used to retrieve a copy of the current map sorted by the key.

The default sorting order of the keys is ascending. However, you can pass an optional comparison function that compares the arguments and returns an integer value less than, equal to, or greater than zero if the first argument is respectively less than, equal to, and greater than the second argument.

Syntax

Following is the syntax of the PHP Ds\Map::ksorted() function −

public Ds\Map::ksorted(callable $comparator = ?): Ds\Map

Parameters

Following is the parameter of this function −

• comparator − An optional comparison function compares the specified arguments.

Following is the syntax of the comparator function −

callback(mixed $a, mixed $b): int

Return value

This function returns a copy of the map, sorted by key.

Example 1

The following program demonstrates the usage of the PHP Ds\Map::ksorted() function −

<?php 
   $map = new \Ds\Map([2 => 20, 1 => 10, 3 => 30]);
   echo "The map elements are: \n";
   print_r($map);
   echo "The sorted map by key: \n"; 
   #using the ksorted() function
   print_r($map->sorted());
?> 

Output

The above program produces the following output −

The map elements are:
Ds\Map Object
(
    [0] => Ds\Pair Object
        (
            [key] => 2
            [value] => 20
        )

    [1] => Ds\Pair Object
        (
            [key] => 1
            [value] => 10
        )

    [2] => Ds\Pair Object
        (
            [key] => 3
            [value] => 30
        )

)
The sorted map by key:
Ds\Map Object
(
    [0] => Ds\Pair Object
        (
            [key] => 1
            [value] => 10
        )

    [1] => Ds\Pair Object
        (
            [key] => 2
            [value] => 20
        )

    [2] => Ds\Pair Object
        (
            [key] => 3
            [value] => 30
        )

)

Example 2

Following is another example of the PHP Ds\Map::ksorted() function. We use this function to retrieve the sorted map by the key of this map (["a" => "Tutorials", "c" => "Point", "b" => "India"]) −

<?php 
   $map = new \Ds\Map(["a" => "Tutorials", "c" => "Point", "b" => "India"]);
   echo "The map elements are: \n";
   foreach($map as $key=>$value){
	   echo "[".$key."] = ".$value."\n";
   }
   echo "\nThe sorted map by key: \n"; 
   #using the ksorted() function
   $new_map = $map->ksorted();
   foreach($new_map as $key=>$value){
	   echo "[".$key."] = ".$value."\n";
   }
?>

Output

After executing the above program, it will display the following output −

The map elements are:
[a] = Tutorials
[c] = Point
[b] = India

The sorted map by key:
[a] = Tutorials
[b] = India
[c] = Point

Example 3

If an optional comparator function is provided, it compares the map elements and returns an integer value based on the comparison −

<?php  
   $map = new \Ds\Map([2 => 'a', 0 => 'b', 1 => 'c']);
   echo "The map elements are: \n";
   foreach($map as $key=>$value){
	   echo "[".$key."] = ".$value."\n";
   }
   echo "The sorted map by key \n";
   #using ksorted() & comparator function
   $new_map = $map->ksorted(function($a, $b){
	   return $a$b;
   });
   foreach($new_map as $key=>$value){
	   echo "[".$key."] = ".$value."\n";
   } 
?>

Output

Once the above program is executed, it will generate the following output −

The map elements are:
[2] = a
[0] = b
[1] = c
The sorted map by key
[0] = b
[1] = c
[2] = a