After merging PHP arrays, how to detect whether the merged elements already exist?

There are three ways to determine whether the element exists in the merged PHP array: 1. Use the in_array() function to check whether the element exists in the array. 2. Use the array_key_exists() function to check whether the specified key exists in the array. 3. Use array_values() to convert the array to an array containing only numeric keys, and then use the in_array() function to check whether the element exists.

PHP How to detect whether an element exists after merging arrays

Introduction

PHP The array merge operation in can merge multiple arrays into a new array. However, when the merged array contains duplicate elements, determining whether the element is present can be challenging. This article will introduce three methods for detecting the existence of elements in the merged array:

Method 1: Use in_array()

##in_array() Function is used to check if an element is present in an array. For merged arrays, we can use this function to detect whether a specific element exists:

$a1 = ['foo', 'bar'];
$a2 = ['baz', 'bar'];

$merged = array_merge($a1, $a2);

if (in_array('baz', $merged)) {
    echo "元素 'baz' 存在于合并后的数组中。";
} else {
    echo "元素 'baz' 不存在于合并后的数组中。";
}

Method 2: Use array_key_exists()

array_key_exists() Function checks whether a specific key exists in an array. For merged arrays, we can use this function to detect whether an element exists as a key:

$a1 = ['foo' => 1, 'bar' => 2];
$a2 = ['baz' => 3, 'bar' => 4];

$merged = array_merge($a1, $a2);

if (array_key_exists('baz', $merged)) {
    echo "元素 'baz' 存在于合并后的数组中。";
} else {
    echo "元素 'baz' 不存在于合并后的数组中。";
}

Method 3: Use array_values() and in_array()

In some cases, the merged array may contain elements stored with non-numeric keys. In this case, we can use the

array_values() function to convert the array to an array containing only numeric keys, and then use the in_array() function to check if the element exists:

$a1 = ['foo', 'bar'];
$a2 = ['baz', 'qux' => 'something'];

$merged = array_merge($a1, $a2);

$values = array_values($merged);
if (in_array('baz', $values)) {
    echo "元素 'baz' 存在于合并后的数组中。";
} else {
    echo "元素 'baz' 不存在于合并后的数组中。";
}

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