How to sort strings in php

Implementation steps: 1. Use the str_split() function to convert the string into a character array, the syntax is "str_split(string)"; 2. Use the asort() or arsort() function to ascend the character array Sort or sort in descending order, the syntax is "asort (character array)" or "arsort (character array)"; 3. Use the implode() function to convert the sorted character array back to a string, the syntax is "implode (sorted character array)" .

The operating environment of this tutorial: windows7 system, PHP version 8.1, DELL G3 computer

In PHP, you can convert the string to Character array, using array sorting function to sort strings.

Implementation steps:

Step 1: Use the str_split() function to convert the string into a character array

str_split( ) function can split the string according to the specified length of the array element, split the string into substrings of the specified length, and pass them into the array one by one as array elements.

str_split(string,length)

• string: Required. Specifies the string to be split.

• #length: Optional. Specifies the length of each array element. The default is 1.​

  If length is less than 1, the str_split() function will return FALSE. If length is greater than the length of the string, the entire string will be returned as the only element of the array.

You only need to set the second parameter of the str_split() function to 1, or omit it to convert the string into a character array.

<?php  
header("content-type:text/html;charset=utf-8");
$str="hacdrwe";
echo "原字符串：";
var_dump($str);
echo "字符串转字符数组：";
$arr=str_split($str);
var_dump($arr);
?>

Step 2: Use the array sorting function asort() or arsort() to sort the character array

• asort() function sorts the associative array in ascending order by key value.

• The arsort() function sorts an associative array in descending order by key value.

echo "升序排序：";
asort($arr);
var_dump($arr);
echo "降序排序：";
arsort($arr);
var_dump($arr);

Step 3: Use the implode() function to convert the sorted character array back to a string

implode() function can convert a one-dimensional array into a string. The syntax is as follows:

implode($glue,$arr)

##ParameterDescriptionOptional. Used to set a string, indicating that $glue is used to connect each element of the array together. By default, $glue is an empty string. Required. Arrays to be combined into strings.

$glue
$arr

#implode() function returns a string composed of array elements and the "$glue" character.

$glue in this example can be omitted

echo "升序排序：";
asort($arr);
var_dump($arr);
$newStr1=implode("",$arr);
var_dump($newStr1);

echo "降序排序：";
arsort($arr);
var_dump($arr);
$newStr2=implode($arr);
var_dump($newStr2);

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