How to determine how many duplicate values ​​there are in an array in php

Method: 1. Use the "$arr2=array_count_values($arr)" statement to count the number of occurrences of all values ​​in the array; 2. Use the foreach statement to traverse the "$arr2" array to determine whether the number of occurrences of the array value is Greater than 1; 3. Count the number of times greater than 1 to know the number of repeated values ​​in the array.

The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

php judgment array How many duplicate values ​​are there

In php, the array_count_values() function can be used to determine how many duplicate values ​​there are in the array

array_count_values() function is used Count the number of occurrences of all values ​​in an array.

<?php
header("Content-type:text/html;charset=utf-8");
$arr=array("A","Cat","Dog","A","Dog",1,2,3,3,2,1);
echo "原数组:";
var_dump($arr);
echo "数组各值的出现次数:";
$arr2=array_count_values($arr);
var_dump($arr2);
?>

It can be seen that the array_count_values() function will return an associative array, the key name of its element is the value of the original array, and the key value is the value that appears in the original array frequency.

In the number of occurrences, any value greater than 1 is a duplicate value. We only need to count the number.

<?php
header("Content-type:text/html;charset=utf-8");
$arr=array("A","Cat","Dog","A","Dog",1,2,3,3,2,1);
$arr2=array_count_values($arr);
$count = 0;
foreach($arr2 as $value){
	if($value>1){
		$count ++;
	}
}
echo "数组中的重复值有：".$count;
?>

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