How to calculate the difference of an array using key name comparison in PHP

PHP editor Xinyi will introduce to you today how to use key name comparison to calculate the difference set of arrays. In PHP, we can use the array_diff_key() function to achieve this function. This function accepts two or more array parameters and returns a new array containing all elements with different keys in the array. This way we can easily compare the keys of two arrays and find the difference between them. Let's take a look at how to use the array_diff_key() function to achieve this function!

PHP uses key name comparison to calculate array difference

Preface

The array difference set is the only element set in the two arrays that exists in one array but not in the other array. In php, array differences can be calculated efficiently by comparing key names.

method

The following is how to calculate the array difference using key name comparison:

1. Initialize the difference array: Create a new array $diffArray Used to store the difference elements.

2. Traverse the first array: Use foreach to loop through the first array $array1.

3. Check if the key name exists: For each key name $key, check if it exists in the second array $array2.

4. Add to the difference set: If the key name does not exist in $array2, add the key name and its value to $diffArray.

The following example shows how to use key name comparison to calculate the difference set:

<?php
//Initialize array
$array1 = ["a" => 1, "b" => 2, "c" => 3];
$array2 = ["b" => 3, "d" => 4];

//Initialize the difference array
$diffArray = [];

// Traverse the first array
foreach ($array1 as $key => $value) {
// Check if the key name exists
if (!array_key_exists($key, $array2)) {
//Add to difference set
$diffArray[$key] = $value;
}
}

//Print difference set
print_r($diffArray);
?>

Output:

Array
(
[a] => 1
[c] => 3
)

Efficiency considerations

Using the key name comparison method can efficiently calculate the array difference because it avoids repeatedly traversing the second array. The average time complexity is O(n), where n is the number of elements in the first array.

Other methods

In addition to key name comparison, there are other methods for calculating array differences, such as:

• Use array_diff_key() function
• Use array_diff_assoc() function
• Manually traverse and compare key names and values

Which method to choose depends on the size of the array and specific requirements.

in conclusion

Use key name comparison to quickly and efficiently calculate array differences. This is a widely used technique because it is simple to understand and performs well.

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