How to apply a user-defined callback function to calculate array key-value intersection using the array_walk_uintersect_assoc function in PHP

In PHP, a variety of array functions are provided to implement array operations and processing. One of the very useful functions is the array_walk_uintersect_assoc function, which can calculate the key-value intersection of the array through a user-defined callback function. This article will detail how to use this function and how to write a custom callback function.

1. Basic syntax of array_walk_uintersect_assoc function

array_walk_uintersect_assoc(array1, array2, array3, ..., "user_defined_function", data)

This function accepts multiple parameters, The first parameter array1, the second parameter array2, the third parameter array3, etc. represent the array list to be compared, and there can be multiple arrays in sequence. "user_defined_function" represents the user-defined callback function to be compared, and the last parameter data is optional and can be used in the callback function.

The return value of this function is an array, which contains the intersection of key values ​​of all input arrays.

2. Write a user-defined callback function

When using the array_walk_uintersect_assoc function to calculate the intersection of array key values, you need to write a user-defined callback function to implement specific comparison operations. An example is given below:

function custom_function($a,$b)
{

if ($a===$b)
{
    return 0;
}
elseif ($a > $b)
{
    return 1;
}
else{
    return -1;
}

}

This function accepts two parameters $a and $b , used to compare the values ​​​​of two elements, if they are equal, return 0; if $a is greater than $b, return 1; otherwise return -1.

3. Use array_walk_uintersect_assoc function to calculate array key-value intersection

The following is an example to demonstrate how to use array_walk_uintersect_assoc function and custom callback function to calculate key-value intersection:

$ arra1 = array("a" => "apple", "b" => "banana", "c" => "cherry");
$arra2 = array("d" => " apple", "b" => "berry", "f" => "fig");
$arra3 = array("b" => "bubba", "f" => "filbert ", "g" => "grape");

$result = array_walk_uintersect_assoc($arra1, $arra2, $arra3, "custom_function");

print_r($result);

The above code will return an array containing the intersection of key values ​​of the three input arrays. In this example, the value "banana" for key "b" is equal to the value "berry" for key "b", so they are included in the resulting array. At the same time, key "a" and key "d" will also be included in the result array.

4. Summary

This article explains how to use the array_walk_uintersect_assoc function in PHP and a user-defined callback function to calculate the intersection of array key values. When using this function, you need to first define a callback function, and then use the function name as the fifth parameter of the array_walk_uiintersect_assoc function. In this way, you can write array processing code very conveniently.

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