How to determine whether a string is repeated in php

Judgment steps: 1. Use str_split() to convert the string into a character array, the syntax "str_split (string)"; 2. Use array_unique() to remove duplicate values ​​​​in the character array, the syntax "array_unique( Character array)" will return a deduplication array; 3. Use count() to obtain the length of the character array and the deduplication array; 4. Determine whether the lengths of the two arrays are equal, the syntax is "Character array length == deduplication array length" , if equal, the strings are not repeated.

The operating environment of this tutorial: windows7 system, PHP8.1 version, DELL G3 computer

In php, you can use arrays To determine whether the string is repeated.

Judgment steps:

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

## The #str_split() function splits a string into characters, and these characters form an array.

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);   
$str="Helloele";
var_dump($str);
$arr=str_split($str);
var_dump($arr);
?>

Step 2: Use array_unique() to remove duplicate values ​​in the character array and return the deduplicated array

array_unique () function is used to remove duplicate values ​​from an array. If two or more array values ​​are the same, only the first value is retained and the other values ​​are removed.

$res=array_unique($arr);
var_dump($res);

Step 3: Use the count() function to get the length of the character array and deduplication array

The count() function can Count the number of all elements in the array, that is, get the array length.

$len1=count($arr);
$len2=count($res);

Step 4: Determine whether the lengths of the two arrays are equal

$len1==$len2

• If the lengths of the two arrays are equal, there are no duplicate values ​​in the arrays

• If the lengths of the two arrays are not equal, it means that an element has been removed, that is, there are duplicate values ​​in the array.

Complete code:

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);   
$str="Helloele";
var_dump($str);
$arr=str_split($str);
var_dump($arr);

$res=array_unique($arr);
var_dump($res);

$len1=count($arr);
$len2=count($res);
if($len1==$len2){
	echo "字符串不重复";
}else{
	echo "字符串有重复";
}

?>

## Recommended learning: "

PHP Video Tutorial

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