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)

##ParameterDescriptionRequired. Specifies the value to search for in the array. Required. Specifies the array to search.             Optional. If this parameter is set to TRUE, the in_array() function checks whether the data being searched is of the same type as the value of the array.

search
array
strict

Return value: TRUE if the value is found in the array, FALSE otherwise.

Example:

<?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

The array_search() function searches for a key value in the array and returns the corresponding key name.

You can also use this function to query whether a certain value exists in the array. If it exists, the corresponding key name will be returned. If it does not exist, it will return false.

Syntax:

array_search(value,array,strict)

ParametersDescriptionRequired. Specifies the key value to search for in the array. Required. Specifies the array to be searched. Optional. If this parameter is set to TRUE, the function searches the array for elements of the same data type and value. Possible values:

value
array
strict	true false - default If set to true, the type of the given value in the array is checked, the number 5 and the string 5 are different (see Example 2).

Return value:

• 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.

Example:

<?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);
?>

Recommended study: "

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