How to detect whether there is a specified value in an array in php

3 methods: 1. Use foreach statement and "==" operator, syntax "foreach($arr as $v){if($v==specified value){//exists}}" . 2. Use in_array(), the syntax is "in_array("specified value", array)", if TRUE is returned, it exists, otherwise it does not exist. 3. Use array_search(), the syntax is "array_search("specified value", array)". If the value exists, the corresponding key name will be returned, otherwise false will be returned.

The operating environment of this tutorial: Windows 7 system, PHP version 8.1, DELL G3 computer

php detection array Are there three ways to specify a value?

Method 1: Use the foreach statement and the "==" operator

• foreach statement loops through the array

• In the loop body, use the "==" operator to compare whether the current element is equal to the specified value

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);   
$arr = array(1,"2",2,3,"4",4,5);
foreach($arr as $v){
	if($v==1){
		echo "指定值存在<br>";
		break;
	}
}
?>

Optimize it:

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);   
function f($arr,$val){
	$con=0;
	foreach($arr as $v){
		if($v==$val){
			$con=1;
			break;
		}else{
		    $con=0;
		}
	}
	if($con==1){
		echo "指定值 $val 存在<br>";
	}else{
	    echo "指定值 $val 不存在<br>";
	}
}

$sites = array(1,"2",2,3,"4",4,5);
f($sites,"1");
f($sites,2);
f($sites,"4");
?>

Method 2: Use in_array() function

In php , if you want to query whether a certain value exists in the array, you can directly use the built-in function in_array()

in_array() function to search whether the specified value exists in the array. Syntax format:

in_array ( $search , $array ,$strict)

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);   
function f($arr,$val){
	if (in_array($val, $arr)){
		echo "指定值 $val 存在<br>";
	}else{
	    echo "指定值 $val 不存在<br>";
	}
}

$sites = array(1,"2",2,3,"4",4,5);
f($sites,"1");
f($sites,2);
f($sites,6);
?>

Method 3: Use array_search() function

array_search(value,array,strict)

• If the specified key value is found in the array, return the corresponding key name, otherwise return FALSE . If a key value is found more than once in the array, the key name matching the first found key value is returned.

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);   
function f($arr,$val){
	$res=array_search($val, $arr);
	var_dump($res);
}

$sites = array(1,"2",2,3,"4",4,5);
f($sites,"1");
f($sites,2);
f($sites,6);
?>

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