How to extract unique values ​​from an array in php

Extraction steps: 1. Use the array_count_values() function to count the number of occurrences of elements in the array. The syntax "array_count_values ​​(original array)" will return an associative array whose key name is the value of the original array. The key value is the number of times the value appears in the original array; 2. Use the array_keys() function to obtain the element with the number of occurrences 1, that is, extract the key name of the element with the key value 1 in the associative array, the syntax "array_keys(associative array ,1)".

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

In PHP, you can use the array_count_values() function and array_keys() function to extract unique values ​​in the array.

Implementation steps:

Step 1: Use the array_count_values() function to count the number of occurrences of elements in the array

array_count_values( ) function can count the number of occurrences of all values ​​in the array; will return an associative array, the key name of its element is the value of the original array, and the key value is the number of times the value appears in the original array .

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);   
$arr=array(1,"A","Cat",2,"Dog","A",3,4,5,5,3,1);
echo "原数组";
var_dump($arr);
$con=array_count_values($arr);
echo "各数组元素的出现次数：";
var_dump($con);

?>

Step 2: Use the array_keys() function to extract unique values ​​in the array

Values ​​with a count of 1, Just don't repeat the value.

Just use the array_keys() function to get the key name corresponding to the element with a key value of 1 in the returned associative array.

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);   
$arr=array(1,"A","Cat",2,"Dog","A",3,4,5,5,3,1);
echo "原数组";
var_dump($arr);
$con=array_count_values($arr);
echo "各数组元素的出现次数：";
var_dump($con);
$res=array_keys($con,1);
echo "数组中的不重复值：";
var_dump($res);
?>

Description:

array_key() function can get some or all key names in the array

array_keys($array [, $search_value = null [, $strict = false]])

Parameter description is as follows:

• $array: required parameter, which is the array to be operated;
• $search_value: optional parameter, if the parameter is empty, the function will return the array All key names in, if this parameter is specified, the function will only return the key name with the value $search_value;
• $strict: Optional parameter to determine whether to use strict mode when searching, $ strict defaults to false, which is non-strict mode. When searching, only types are compared, not types. If $strict is set to true, which is strict mode, values ​​and types are compared at the same time during search, which is equivalent to ===.

array_keys() function will return the obtained array key name in the form of an array.

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