How to compare differences of array keys using array_diff_key function in PHP

In PHP programming, comparing two arrays for equality is an important task. Normally, we use the array_diff function to compare the differences of arrays, but when comparing the keys of arrays, we will encounter some problems. At this time, we can use the array_diff_key function in PHP to compare the differences in array keys.

The array_diff_key function can compare the keys in two arrays and return the keys that exist in the first array but not in the second array. This function returns an array containing the key names, not the difference between the two arrays.

The following is the syntax of the array_diff_key function:

array array_diff_key (array $array1, array $array2 [, array $...])

Among them, $array1 represents the An array, $array2 represents the second array, ... represents optional multiple arrays.

Below we use a simple example to illustrate how to use the array_diff_key function.

Suppose we have two arrays $car1 and $car2, which store two brands of cars respectively, as shown below:

$car1 = array("Honda"=>"Accord ", "Toyota"=>"Camry", "Nissan"=>"Teana");
$car2 = array("Honda"=>"Civic", "Toyota"=>"Prado" , "Ford"=>"Fox");

When we use the array_diff_key function to compare these two arrays, the code is as follows:

$result = array_diff_key($car1, $car2) ;

At this time, what is stored in the $result array will be the keys that exist in the $car1 array but do not exist in the $car2 array, that is, the Nissan key. The final result is as follows:

array("Nissan"=>"天灁");

If we want to compare the keys of multiple arrays, we can pass these arrays as variable parameters to the array_diff_key function, the code is as follows:

$newCar = array("Honda"=>"Spirit", "Toyota"=>"Highlander");
$result = array_diff_key($car1, $car2, $newCar);

At this time, the $result array will store the keys that exist in the $car1 array but do not exist in the $car2 and $newCar arrays, that is, the Nissan keys. The final result is as follows:

array("Nissan"=>"天灁");

If we want to compare the values ​​of two arrays instead of the keys, we can use the array_diff function.

In general, the array_diff_key function is a function used to compare the keys in two arrays and return the keys that exist in the first array but not in the second array. By using this function, we can easily compare the differences of the keys of two arrays and gain a better knowledge of PHP programming.

The above is the detailed content of How to compare differences of array keys using array_diff_key function in PHP. For more information, please follow other related articles on the PHP Chinese website!