Loading... ## PHP Functions For Sorting Arrays In the previous chapter you’ve learnt the essentials of PHP arrays i.e. what arrays are, how to create them, how to view their structure, how to access their elements etc. You can do even more things with arrays like sorting the elements in any order you like. PHP comes with a number of built-in functions designed specifically for sorting array elements in different ways like alphabetically or numerically in ascending or descending order. Here we’ll explore some of these functions most commonly used for sorting arrays. * sort() and rsort() — For sorting indexed arrays * asort() and arsort() — For sorting associative arrays by value * ksort() and krsort() — For sorting associative arrays by key ## Sorting Indexed Arrays in Ascending Order The sort() function is used for sorting the elements of the indexed array in ascending order (alphabetically for letters and numerically for numbers). ```php <?php // Define array $colors = array("Red", "Green", "Blue", "Yellow"); // Sorting and printing array sort($colors); print_r($colors); ?> ``` This print\_r() statement gives the following output: ```php Array ( [0] => Blue [1] => Green [2] => Red [3] => Yellow ) ``` Similarly you can sort the numeric elements of the array in ascending order. ```php <?php // Define array $numbers = array(1, 2, 2.5, 4, 7, 10); // Sorting and printing array sort($numbers); print_r($numbers); ?> ``` This print\_r() statement gives the following output: ```php Array ( [0] => 1 [1] => 2 [2] => 2.5 [3] => 4 [4] => 7 [5] => 10 ) ``` ## Sorting Indexed Arrays in Descending Order The rsort() function is used for sorting the elements of the indexed array in descending order (alphabetically for letters and numerically for numbers). ```php <?php // Define array $colors = array("Red", "Green", "Blue", "Yellow"); // Sorting and printing array rsort($colors); print_r($colors); ?> ``` This print\_r() statement gives the following output: ```php Array ( [0] => Yellow [1] => Red [2] => Green [3] => Blue ) ``` Similarly you can sort the numeric elements of the array in descending order. ```php <?php // Define array $numbers = array(1, 2, 2.5, 4, 7, 10); // Sorting and printing array rsort($numbers); print_r($numbers); ?> ``` This print\_r() statement gives the following output: ```php Array ( [0] => 10 [1] => 7 [2] => 4 [3] => 2.5 [4] => 2 [5] => 1 ) ``` ## Sorting Associative Arrays in Ascending Order By Value The asort() function sorts the elements of an associative array in ascending order according to the value. It works just like sort(), but it preserves the association between keys and its values while sorting. ```php <?php // Define array $age = array("Peter"=>20, "Harry"=>14, "John"=>45, "Clark"=>35); // Sorting array by value and print asort($age); print_r($age); ?> ``` This print\_r() statement gives the following output: ```php Array ( [Harry] => 14 [Peter] => 20 [Clark] => 35 [John] => 45 ) ``` ## Sorting Associative Arrays in Descending Order By Value The arsort() function sorts the elements of an associative array in descending order according to the value. It works just like rsort(), but it preserves the association between keys and its values while sorting. ```php <?php // Define array $age = array("Peter"=>20, "Harry"=>14, "John"=>45, "Clark"=>35); // Sorting array by value and print arsort($age); print_r($age); ?> ``` This print\_r() statement gives the following output: ```php Array ( [John] => 45 [Clark] => 35 [Peter] => 20 [Harry] => 14 ) ``` ## Sorting Associative Arrays in Ascending Order By Key The ksort() function sorts the elements of an associative array in ascending order by their keys. It preserves the association between keys and its values while sorting, same as asort() function. ```php <?php // Define array $age = array("Peter"=>20, "Harry"=>14, "John"=>45, "Clark"=>35); // Sorting array by key and print ksort($age); print_r($age); ?> ``` This print\_r() statement gives the following output: ```php Array ( [Clark] => 35 [Harry] => 14 [John] => 45 [Peter] => 20 ) ``` ## Sorting Associative Arrays in Descending Order By Key The krsort() function sorts the elements of an associative array in descending order by their keys. It preserves the association between keys and its values while sorting, same as arsort() function. ```php <?php // Define array $age = array("Peter"=>20, "Harry"=>14, "John"=>45, "Clark"=>35); // Sorting array by key and print krsort($age); print_r($age); ?> ``` This print\_r() statement gives the following output: ```php Array ( [Peter] => 20 [John] => 45 [Harry] => 14 [Clark] => 35 ) ``` Last modification：September 9, 2024 © Allow specification reprint Like 如果觉得我的文章对你有用，请随意赞赏