How to determine whether a certain value exists in an array in php

In PHP, arrays are a very common data type that can be used to store multiple values ​​and reference these values ​​with specific keys. During the development process, sometimes we need to find a specific element value in the array to determine whether it exists. This article will introduce how to determine whether an array contains an element value in PHP.

1. Use the in_array function

PHP provides the in_array function, which can search whether the specified value exists in an array and return a Boolean value. The usage is as follows:

$myArray = array('apple', 'orange', 'banana', 'grape');
if (in_array('orange', $myArray)) {
    echo "存在";
} else {
    echo "不存在";
}

The result output is: exists

If we find a value that does not exist, for example:

if (in_array('watermelon', $myArray)) {
    echo "存在";
} else {
    echo "不存在";
}

The result output is: does not exist

2. Use the array_search function

PHP’s other built-in function array_search can also be used to find the position of a specified value in an array and return its key value. The usage method is as follows:

$myArray = array('apple', 'orange', 'banana', 'grape');
if (($key = array_search('orange', $myArray)) !== false) {
    echo "存在，位置为：".$key;
} else {
    echo "不存在";
}

The result output is: exists, the position is: 1

It should be noted that if the value found in the array exists in multiple positions, the array_search function will only return First position.

3. Use the isset function and key-value reference

If we just need to determine whether a specified key exists in the array, we can use the isset function or the key-value reference method. For example:

$myArray = array('apple'=>'10', 'orange'=>'20', 'banana'=>'30', 'grape'=>'40');
if(isset($myArray['banana'])){
    echo "存在";
}else{
    echo "不存在";
}

The result output is: Existence

If we are more concerned about whether the value corresponding to a certain key in the array exists, rather than whether the key itself exists, we can also use the same method:

$myArray = array('apple'=>'10', 'orange'=>'20', 'banana'=>'30', 'grape'=>'40');
if(isset($myArray['banana'])){
    echo "存在，值为：".$myArray['banana'];
}else{
    echo "不存在";
}

The result output is: exists, the value is: 30

Summary

This article introduces how to determine whether an array contains a certain element value in PHP. We can use the in_array function, array_search function, isset function and key-value reference method to achieve this. Different methods can be used to choose according to actual needs.

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