Use array_map() to convert arrays and then use array_diff_uassoc() to compare

How to compare by first converting an array with array_map() and then using array_diff_uassoc()?

In PHP, array_map() and array_diff_uassoc() are two very useful functions that can help us process and compare arrays in different scenarios. This article will introduce how to convert arrays using array_map() first, then use array_diff_uassoc() for comparison, and give specific examples.

1. Introduction to array_map() function

The array_map() function can convert each element of an array through a callback function. The basic syntax is as follows:

 array_map(callable $callback, array $array1, array ...$arrays);

• $callback : A callback function used to process array elements.

• $array1, ...$arrays : One or more input arrays.

array_map() returns a new array where each element is a value processed by the $callback function.

2. Introduction to array_diff_uassoc() function

The array_diff_uassoc() function is used to compare two or more arrays, returning elements in the first array with neither key names nor values ​​compared to other arrays. Unlike the regular array_diff() , array_diff_uassoc() allows us to provide a custom comparison function to compare key names.

The basic syntax is as follows:

 array_diff_uassoc(array $array1, array $array2, callable $key_compare_func);

• $array1 : The first array to be compared.

• $array2 : The second array to compare.

• $key_compare_func : A callback function used to compare array key names.

3. Example: Use array_map() and array_diff_uassoc() in combination

Now let's take a look at a practical example, how to convert the value of an array using array_map() , and then use array_diff_uassoc() for comparison.

Suppose we have two arrays representing the prices and names of the two sets of products:

 $products1 = [
    101 => "Apple",
    102 => "Banana",
    103 => "Orange"
];

$products2 = [
    101 => "Apple",
    102 => "Grapes",
    104 => "Mango"
];

// price
$prices1 = [
    101 => 3,
    102 => 2,
    103 => 1
];

$prices2 = [
    101 => 3,
    102 => 2.5,
    104 => 1.5
];

Suppose we want to convert the product name to capital letters and use array_diff_uassoc() to compare elements with different prices and same key names in two price arrays.

 // Convert the product name to capital letters first
$products1 = array_map('strtoupper', $products1);
$products2 = array_map('strtoupper', $products2);

// use array_diff_uassoc 比较price数组（The key name is the same，price不同）
$price_diff = array_diff_uassoc($prices1, $prices2, function ($key1, $key2) {
    return $key1 - $key2;
});

print_r($price_diff);

4. Explain the code

1. We use array_map('strtoupper', $products1) and array_map('strtoupper', $products2) to convert product names to uppercase letters. This way we can ensure that the comparison of names is not affected by upper and lower case.

2. array_diff_uassoc() is used to compare price arrays. We provide a simple callback function for comparing key names ( $key1 - $key2 ). If the key names of the two arrays are the same but the corresponding prices are different, array_diff_uassoc() will return these elements.

5. Output result

When running the above code, we get an output:

 Array
(
    [102] => 2
    [104] => 1.5
)

In this example, the prices of product IDs 102 and 104 are different, so they are returned.

Summarize

This article describes how to use the array_map() and array_diff_uassoc() functions in PHP. We first use array_map() to convert elements in the array, and then compare elements with different key names and corresponding values ​​in two arrays through array_diff_uassoc() . In this way, we can flexibly process and compare arrays to suit different needs.

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