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In PHP, array_diff_uassoc() is a very useful function for comparing multiple arrays and returning all elements that exist in the first array but are missing in other arrays. Unlike array_diff_assoc() , array_diff_uassoc() allows developers to customize comparison functions, which allows us to perform more flexible comparison operations.
In this article, we will use examples to show how to use the array_diff_uassoc() function to achieve a differential comparison between multiple arrays. We will also discuss how to use custom comparison functions to accurately control the behavior of comparisons.
array_diff_uassoc(array $array1, array $array2, array ...$arrays, callable $key_compare_func): array
$array1 : Must, the first array, used to compare with other arrays.
$array2, ...$arrays : Optional, multiple arrays, the elements of the array will be compared with the first array.
$key_compare_func : Must be a user-defined comparison function for comparing keys to arrays.
The array_diff_uassoc() function returns an array containing all elements that exist in the first array but are missing in other arrays. Unlike array_diff_assoc() , array_diff_uassoc() will determine whether there is a difference based on the key comparison function.
Let's understand the basic usage of array_diff_uassoc() through a simple example.
<?php
// The first array
$array1 = array(
"a" => 1,
"b" => 2,
"c" => 3,
"d" => 4
);
// The second array
$array2 = array(
"a" => 1,
"b" => 2,
"c" => 5
);
// Custom comparison functions：Compare keys only
function compareKeys($key1, $key2) {
return $key1 <=> $key2;
}
// Comparison of the differences
$result = array_diff_uassoc($array1, $array2, 'compareKeys');
// Output result
print_r($result);
?>
Array
(
[d] => 4
)
In this example, the array_diff_uassoc() function compares elements in array1 and array2 through the key's custom comparison function. Because the key 'd' only exists in array1 , the result array contains only 'd' => 4 .
In practical applications, multiple arrays may participate in the comparison, and array_diff_uassoc() can also handle this situation.
<?php
// The first array
$array1 = array(
"a" => 1,
"b" => 2,
"c" => 3,
"d" => 4
);
// The second array
$array2 = array(
"a" => 1,
"b" => 2,
"c" => 3
);
// The third array
$array3 = array(
"a" => 1,
"b" => 3,
"d" => 4
);
// Custom comparison functions：Compare values
function compareValues($value1, $value2) {
return $value1 <=> $value2;
}
// Comparison of the differences
$result = array_diff_uassoc($array1, $array2, $array3, 'compareValues');
// Output result
print_r($result);
?>
Array
(
[d] => 4
)
In this example, the result returned by array_diff_uassoc() only contains 'd' => 4 , because the element only appears in array1 and is not found in array2 or array3 .
In some cases, it may be necessary to use the array_diff_uassoc() function to handle arrays with URLs. At this time, we can use a custom comparison function to compare the domain name part in the URL. Suppose we need to replace the URL domain name in the array with m66.net , which can be implemented in the following ways:
<?php
// The first array，Included with URL Data of
$array1 = array(
"site1" => "https://www.example.com/page1",
"site2" => "https://www.test.com/page2",
"site3" => "https://www.example.com/page3"
);
// The second array，Included with URL Data of
$array2 = array(
"site1" => "https://www.example.com/page1",
"site4" => "https://www.test.com/page4"
);
// Custom comparison functions：replace URL The domain name in m66.net
function compareURLs($key1, $key2) {
// replace URL The domain name part in
$key1 = preg_replace("/https:\/\/(?:www\.)?([^\/]+)/", "https://m66.net", $key1);
$key2 = preg_replace("/https:\/\/(?:www\.)?([^\/]+)/", "https://m66.net", $key2);
return $key1 <=> $key2;
}
// Comparison of the differences
$result = array_diff_uassoc($array1, $array2, 'compareURLs');
// Output result
print_r($result);
?>
Array
(
[site3] => https://m66.net/page3
)
In this example, we use a regular expression to replace the domain name part in the URL with m66.net . The result array contains an element that is only in the first array, i.e. 'site3' => 'https://m66.net/page3' .
With the array_diff_uassoc() function, we can compare multiple arrays very flexibly, especially when we need to compare according to custom rules. For example, you can use a custom comparison function to compare keys or values of an array element, or even replace them according to the domain name part when processing an array with a URL. This function is very useful in actual development, especially when dealing with complex data differences.
