Array functions in PHP8: Examples of various operations of array_intersect_assoc()

PHP language is a language widely used in web development and server-side script programming. Its powerful array function support is one of the important components of its excellent performance. In PHP8, the new array function array_intersect_assoc() was introduced, which has more efficient performance and more convenient usage when operating associative arrays. This article will introduce the usage of the array_intersect_assoc() function and provide a variety of examples to illustrate its various operation methods and practical application scenarios.

1. Basic usage of array_intersect_assoc()

The array_intersect_assoc() function is used to compare two or more associative arrays and return a new associative array that contains the same values ​​as all input arrays. There are elements with equal keys and values. The syntax is as follows:

array_intersect_assoc(array1,array2,array3,...)

where each input parameter is an associative array, which will be compared to find the same key and value. The return value is a new associative array containing elements with keys and values ​​equal to all input arrays. The following is a simple example:

$array1 = array("a"=>"red","b"=>"green","c"=>"blue");
$array2 = array("a"=>"red","b"=>"blue");
$result = array_intersect_assoc($array1,$array2);
print_r($result);

The output result is:

Array ( [a] => red )

This is because only the elements with key "a" exist in both input arrays and have equal values.

2. The difference between array_intersect_assoc() and array_intersect()

The difference from the array_intersect() function is that the array_intersect_assoc() function not only compares The values ​​of the elements are compared, but also the keys of the elements are compared. Therefore, it detects and handles key-value pair relationships more accurately. Let's look at an example to illustrate this difference:

$array1 = array("a"=>1,"b"=>2,"c"=>3);
$array2 = array(2=>"b",3=>"a",4=>"c");
$result1 = array_intersect($array1,$array2);
$result2 = array_intersect_assoc($array1,$array2);
print_r($result1);
print_r($result2);

The output result is:

Array ( [b] => 2 )
Array ( [a] => 1 )

As you can see, the array_intersect() function only detects the value of the element and finds the same The value "2", and the array_intersect_assoc() function not only finds the element "2" with the same value, but also finds the element "a" with the same key and value. This is one of the differences between the two functions.

3. Comparison operation of multiple arrays

array_intersect_assoc()The function can not only compare two arrays, but also compare multiple arrays. The following example will demonstrate how to compare three arrays:

$array1 = array("a"=>"red","b"=>"green","c"=>"blue");
$array2 = array("a"=>"red","b"=>"blue");
$array3 = array("a"=>"red","b"=>"green");
$result = array_intersect_assoc($array1,$array2,$array3);
print_r($result);

The output result is:

Array ( [a] => red )

This is because only the element with the key "a" exists in the three input arrays and has the value equal.

4. Missing elements

If the keys or values ​​in different input arrays are not equal, they will not be included in the result. If a key is missing from one of the input arrays, that key will not be included in the result. For example:

$array1 = array("a"=>"red","b"=>"green","c"=>"blue");
$array2 = array("a"=>"red","d"=>"blue");
$result = array_intersect_assoc($array1,$array2);
print_r($result);

The output result is an empty array.

5. Preserve key names or ordering of keys

By default, the array_intersect_assoc() function will preserve key names and maintain their relative order in the result array . For example:

$array1 = array("a"=>"red","b"=>"green","c"=>"blue");
$array2 = array("a"=>"red","b"=>"blue");
$result = array_intersect_assoc($array1,$array2);
print_r($result);

The output result is:

Array ( [a] => red [b] => green )

If you want to sort the results in alphabetical order by key name, you can use the ksort() function, as shown below:

$array1 = array("a"=>"red","b"=>"green","c"=>"blue");
$array2 = array("a"=>"red","b"=>"blue");
$result = array_intersect_assoc($array1,$array2);
ksort($result);
print_r($result);

The output result is:

Array ( [a] => red [b] => green )

If you do not retain the key name, but only retain the element value, you can use the array_intersect() function, as shown below:

$array1 = array("red","green","blue");
$array2 = array("red","blue");
$result = array_intersect($array1,$array2);
print_r($result);

The output result is:

Array ( [0] => red [2] => blue )

6. Summary

array_intersect_assoc() function is one of the new array functions introduced in PHP8. It performs comparisons and operations on associative arrays more precise, efficient and convenient. This article provides a variety of examples and introduces how to use it to perform various calculations and operations, including basic usage, differences from the array_intersect() function, comparison operations of multiple arrays, missing elements, retention Key names or sorting of keys, etc. For PHP developers, being familiar with and mastering these operations can make it easier and more efficient to handle various associative array operation requirements.

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