How to compare arrays and delete them in php

PHP is a popular server-side programming language that is widely used when developing web applications. In PHP, it is often necessary to perform operations such as comparing, merging, and deleting arrays to make the array data more complete and reasonable. In this article, you will learn how to compare arrays and delete them in PHP.

1. Compare Arrays

For comparison of PHP arrays, you can use some built-in functions to achieve it. Among them, the following three functions are mainly involved:

• array_diff: used to return the difference between two arrays;
• array_intersect: used to return the difference between two arrays Intersection item;
• array_diff_key: used to return the key value difference item between two arrays.

Take the array_diff function as an example, assuming we have two arrays:

$colors1 = array("red", "green", "blue");
$colors2 = array("black", "red", "yellow");

Then, we can use the following code to compare the different items between the two arrays and return Result:

$result = array_diff($colors1, $colors2);
print_r($result);

The output result is:

Array
(
    [1] => green
    [2] => blue
)

Similarly, you can use the array_intersect function to compare the intersection items between two arrays. In addition, the array_diff_key function can be used to compare key value differences.

2. Delete array elements

In PHP, there are many ways to delete array elements. Several common methods are listed below:

• unset function: You can delete specified elements of the array through the unset function, such as:

$fruit = array('apple', 'orange', 'banana', 'grape');
unset($fruit[2]); // 删除数组中的 banana 元素

• array_splice function: used Delete elements within the specified range in the array. The syntax is:

array_splice($array, $offset, $length);

Among them, $array is the array to be operated; $offset is the specified starting position, calculated from 0; $length is the required The number of elements to remove. The sample code is as follows:

$fruit = array('apple', 'orange', 'banana', 'grape');
array_splice($fruit, 1, 2); // 删除数组中的 orange 和 banana 元素

• array_filter function: You can filter the elements in the array through the callback function and return a collection of elements that meet the conditions. For example:

$fruit = array('apple', 'orange', 'banana', 'grape');
$result = array_filter($fruit, function($item) {
    return $item != 'banana'; // 过滤掉元素值为 banana 的元素
});
print_r($result);

3. Compare arrays and delete specified elements

If you need to compare two arrays in PHP and delete specified elements, you can combine the above comparison arrays And the method of deleting array elements implements the following logic:

• Compare the two arrays to determine the elements that need to be deleted;
• According to the elements that need to be deleted, use the unset or array_splice function to delete the specified element.

Sample code:

$fruit1 = array('apple', 'orange', 'banana', 'grape');
$fruit2 = array('banana', 'grape', 'watermelon');
$intersect = array_intersect($fruit1, $fruit2); // 获取交集
foreach ($intersect as $value) {
    unset($fruit1[array_search($value, $fruit1)]);
}
print_r($fruit1);

In the above code, first use the array_intersect function to obtain the intersection between the two arrays, then use the foreach loop to traverse the intersection, and use the unset function Removes the specified element from the fruit1 array. The final output result is:

Array
(
    [0] => apple
    [1] => orange
)

If the element to be deleted is located in the middle of the array, you can use the array_splice function to achieve this.

Summary

This article mainly introduces how to compare arrays and perform deletion operations in PHP. In the actual development process, comparing and deleting array elements are very common operations, especially when a large amount of data needs to be processed. I hope that readers can master the basic skills and ideas of using PHP to operate arrays through the introduction of this article.

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