How to check if an array contains an element in php

In PHP development, it is often necessary to query whether an array contains a certain element. This process is not difficult. This article will introduce how to query whether an array contains a certain element in PHP.

1. Use the in_array() function to implement

In PHP, we can use the in_array() function to determine whether an array contains an element. The basic syntax of this function is as follows:

bool in_array ( mixed $needle , array $haystack [, bool $strict = FALSE ] )

Among them, $needle is the element to be found, $haystack is the array to be found, and the $strict parameter indicates whether to use strict mode. By default, it is false (loose mode).

If the specified element is queried, the function returns true, otherwise it returns false. The following is a simple application example:

<?php
$arr=array(&#39;apple&#39;,&#39;banana&#39;,&#39;orange&#39;);
if(in_array(&#39;apple&#39;,$arr)){
    echo &#39;存在&#39;;
}else{
    echo &#39;不存在&#39;;
}
?>

In the above code, we first assign an array to the variable $arr, and then use the in_array() function to query whether the array contains the element 'apple'. If it exists, Then output "exists", otherwise output "does not exist".

2. Use the array_search() function to implement

Another function that queries whether an array contains an element is array_search(). This function is somewhat similar to the in_array() function and its basic syntax As follows:

mixed array_search ( mixed $needle , array $haystack [, bool $strict = false ] )

The return value of this function is the key name (key) of the specified element in the array. If it is not found, it returns false. The following is a simple application example:

<?php
$arr=array(&#39;apple&#39;,&#39;banana&#39;,&#39;orange&#39;);
$key=array_search(&#39;banana&#39;,$arr);
if($key!==false){
    echo &#39;存在，key值为&#39;.$key;
}else{
    echo &#39;不存在&#39;;
}
?>

In the above code, we first use the array_search() function to find whether the element 'banana' is contained in the array. If it exists, then output "Exists, key value is $key" , otherwise output "does not exist".

3. Use the array_key_exists() function to implement

If we need to query whether an element exists in the key name of the array, we can use the array_key_exists() function to achieve it. The basic syntax of this function is as follows :

bool array_key_exists ( mixed $key , array $array )

The return value of this function is of Boolean type. If the specified key name exists in the array, it returns true, otherwise it returns false. The following is a simple application example:

<?php
$arr=array(&#39;name&#39;=>'张三','age'=>18,'sex'=>'男');
if(array_key_exists('age',$arr)){
    echo '存在';
}else{
    echo '不存在';
}
?>

In the above code, we first use the array_key_exists() function to determine whether there is an element with the key name 'age' in the array. If it exists, then output "exists", otherwise Output "does not exist".

Summary

Through the above three examples, we can see that PHP provides a variety of methods to query whether an array contains a certain element. Developers can choose the one that suits them according to the actual situation. method to query.

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