PHP compares arrays to see if they are the same

In PHP, comparing arrays to see if they are the same is a very common operation. Normally, to compare two arrays to see if they are the same, even if their elements are in different order, we need to sort them and then compare them one by one. It's not difficult to do, but it does take some time.

In PHP, there are many simple methods to compare arrays to see if they are the same. Below we introduce some commonly used methods.

1. array_diff()

array_diff() function compares two arrays and returns whether it exists in the first array but not in the second array Elements. If the two arrays are exactly equal, an empty array is returned.

The example is as follows:

$array1 = array('a', 'b', 'c');
$array2 = array('a', 'b', 'd');

$res = array_diff($array1, $array2);

if (empty($res)) {
    echo '两个数组相等';
} else {
    echo '两个数组不相等';
}

The above code will output "the two arrays are not equal". This is because the 'c' element in array $array1 does not exist in $array2.

2. array_diff_assoc()

array_diff_assoc() function compares two arrays and returns those that exist in the first array but do not exist in the second array elements, and the keys of those elements are also compared.

The example is as follows:

$array1 = array('a' => 'apple', 'b' => 'banana', 'c' => 'cherry');
$array2 = array('a' => 'apple', 'b' => 'orange', 'c' => 'cherry');

$res = array_diff_assoc($array1, $array2);

if (empty($res)) {
    echo '两个数组相等';
} else {
    echo '两个数组不相等';
}

The above code will output "the two arrays are not equal". This is because the 'banana' element in array $array1 does not exist in $array2, and the 'b' key is also different.

3. array_diff_key()

array_diff_key() function compares two arrays and returns the key that exists in the first array but does not exist in the second array The key of the element. The difference from array_diff() is that array_diff_key() only compares array keys, not the values ​​corresponding to the keys.

The example is as follows:

$array1 = array('a' => 'apple', 'b' => 'banana', 'c' => 'cherry');
$array2 = array('a' => 'apple', 'b' => 'orange', 'd' => 'mango');

$res = array_diff_key($array1, $array2);

if (empty($res)) {
    echo '两个数组相等';
} else {
    echo '两个数组不相等';
}

The above code will output "the two arrays are not equal". This is because the 'c' key in array $array1 does not exist in $array2, and the 'd' key is also different.

4. array_uintersect_assoc()

array_uintersect_assoc() function compares two arrays and returns the elements that exist in both arrays. It also compares the elements of these elements. key. Corresponds to array_diff_assoc().

The example is as follows:

$array1 = array('a' => 'apple', 'b' => 'banana', 'c' => 'cherry');
$array2 = array('a' => 'apple', 'b' => 'orange', 'c' => 'cherry');

function compare($a, $b) {
    if ($a === $b) {
        return 0;
    }

    return ($a < $b) ? -1 : 1;
}

$res = array_uintersect_assoc($array1, $array2, 'compare');

if (count($res) === count($array1) && count($res) === count($array2)) {
    echo '两个数组相等';
} else {
    echo '两个数组不相等';
}

The above code will output "the two arrays are not equal". This is because the 'b' key in array $array2 corresponds to a different value.

The above functions are all PHP built-in functions and can be easily compared. But it should be noted that when comparing arrays, the types of elements are not compared by default. If you need to compare the types of elements, you can use functions with user-defined callbacks such as array_diff_uassoc() and specify the type comparison method in the custom comparison function.

Comparing whether arrays are the same in PHP is not a complicated problem. Depending on different needs, different methods can be chosen.

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