How to determine whether the specified key value exists in a two-dimensional array in PHP

For PHP's two-dimensional array, we often need to determine whether a key-value pair exists in the array. This article will introduce several common methods.

1. Use in_array function

The in_array function can be used to determine whether a value exists in an array, but it can only determine whether a value exists in a one-dimensional array and cannot determine whether it is in a two-dimensional array. key-value pairs. We can use its variant in_array_recursive function to recursively determine whether the key-value pair in the two-dimensional array exists.

Sample code:

function in_array_recursive($needle, $haystack, $strict = false)
{
    foreach ($haystack as $value) {
        if ((!$strict && $needle == $value) || ($strict && $needle === $value)) {
            return true;
        }
        if (is_array($value) && in_array_recursive($needle, $value, $strict)) {
            return true;
        }
    }
    return false;
}

$array = array(
    array('id' => 1, 'name' => '张三'),
    array('id' => 2, 'name' => '李四'),
    array('id' => 3, 'name' => '王五'),
);

if (in_array_recursive(array('id' => 1, 'name' => '张三'), $array)) {
    echo '存在';
} else {
    echo '不存在';
}

2. Use array_column function

array_column function can extract a column in a two-dimensional array as a new one-dimensional array, We can use it to determine whether a key exists in the array.

Sample code:

$array = array(
    array('id' => 1, 'name' => '张三'),
    array('id' => 2, 'name' => '李四'),
    array('id' => 3, 'name' => '王五'),
);

$ids = array_column($array, 'id');

if (in_array(1, $ids)) {
    echo '存在';
} else {
    echo '不存在';
}

3. Use array_search function

array_search function can find the location of a key value in the array, and if found, return the The index of the key, otherwise false is returned. However, it can only find one-dimensional arrays and cannot find key-value pairs in two-dimensional arrays. We can use its third parameter to specify the value of the lookup key.

Sample code:

$array = array(
    array('id' => 1, 'name' => '张三'),
    array('id' => 2, 'name' => '李四'),
    array('id' => 3, 'name' => '王五'),
);

foreach ($array as $key => $value) {
    if (array_search(1, $value)) {
        echo '存在';
        break;
    } else {
        echo '不存在';
    }
}

The above are three common two-dimensional array judgment methods. You can choose the appropriate method according to the specific situation.

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