How to compare differences of associative arrays using array_diff_assoc function in PHP

With the continuous development of technology, web development has become more and more popular. PHP is one of the widely used web development languages. In the process of processing data, it is often necessary to compare the difference between two arrays. At this time we can use the array_diff_assoc function in PHP to achieve this.

The array_diff_assoc function is used to compare the difference between two associative arrays, returning a new array based on the key-value pair. It returns an array that exists in all parameter arrays, but in other Element that does not exist in the parameter array.

The following is the basic syntax of the array_diff_assoc function: array array_diff_assoc ( array $array1 , array $array2 [, array $... ] )

Parameter description:

1. $array1: required. The first associative array.
2. $array2: required. Second associative array.
3. $...: Optional. Other associative arrays to compare.

Let’s learn how to use it through an example.

Example:

<?php
$array1 = array("a" => "red", "b" => "green", "c" => "blue");
$array2 = array("a" => "red", "b" => "blue", "d" => "yellow");
$result = array_diff_assoc($array1, $array2);
print_r($result);
?>

Output result:

Array
(
    [b] => green
    [c] => blue
)

In the above example, we declared two associative arrays $array1 and $array2, each containing different keys. value pair. We then use the array_diff_assoc function to compare the differences between them and assign the result to the variable $result. Finally, we use the print_r() function to output the result and find that the result is an associative array containing two different key-value pairs.

It should be noted that the array_diff_assoc() function is case-sensitive, which means that it will treat key-value pairs with different cases as different elements. If we need to ignore case differences during the comparison, we can first use the array_change_key_case() function to convert all key names to lowercase or uppercase, and then compare.

Example:

<?php
$array1 = array("a" => "red", "B" => "green", "c" => "blue");
$array2 = array("a" => "RED", "b" => "blue", "d" => "yellow");
$array1_lower = array_change_key_case($array1, CASE_LOWER);
$array2_lower = array_change_key_case($array2, CASE_LOWER);

$result = array_diff_assoc($array1_lower, $array2_lower);
print_r($result);
?>

Output result:

Array
(
    [b] => green
    [c] => blue
)

In the above example, we also declared two associative arrays, the difference is that their upper and lower case forms are different. Before comparing, we use the array_change_key_case() function to convert all key names to lowercase, and assign the results to two other variables, $array1_lower and $array2_lower. Then we use the array_diff_assoc() function to compare the two converted associative arrays and find that the result has ignored the difference in case. It should be noted that the array_change_key_case() function has two modes to choose from: CASE_LOWER and CASE_UPPER, which represent conversion to lowercase and uppercase respectively.

Summary:

array_diff_assoc() function is a function in PHP used to compare the difference between associative arrays. It can easily find the difference between two associative arrays and return A new array containing these differential key-value pairs. When using this function, you need to pay attention to the difference in case. You can first use the array_change_key_case() function for unified conversion. Mastering this function can help us process data more conveniently and improve development efficiency.

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