How to remove extracted values ​​from an array in php

In PHP, array is a very commonly used data structure. In applications, we often need to traverse the elements in the array, and during the traversal, we need to dynamically delete the elements that have been taken out to ensure that subsequent traversal operations can proceed normally. This article will introduce how to remove the values ​​that have been taken out of the array in PHP.

1. Basic methods for deleting elements from arrays

PHP provides a variety of methods for deleting elements from arrays. Generally speaking, there are two ways:

1. Use array functions: PHP provides multiple functions to handle arrays, such as array_shift(), array_pop(), unset(), array_splice(), etc. , these functions can be used to delete elements in an array.
2. Use loop traversal: Another way is to use a loop to traverse the array, find the element to be deleted, and delete it using the unset() function.

Let’s first introduce how to use array functions.

1. array_shift() function

array_shift() function removes the first element in the array and returns the value of the element, and the keys of other elements are reordered . The sample code is as follows:

$fruits = array("apple", "banana", "orange");
$firstFruit = array_shift($fruits);
echo $firstFruit; // 输出: apple

This function is very suitable for deleting the first element in the array and need to use the value of the element after deletion.

2. array_pop() function

array_pop() function removes the last element in the array and returns the value of the element. The sample code is as follows:

$fruits = array("apple", "banana", "orange");
$lastFruit = array_pop($fruits);
echo $lastFruit; // 输出: orange

This function is very suitable for deleting the last element in the array and need to use the value of the element after deletion.

3. unset() function

The unset() function is used to delete the specified element in the array. The sample code is as follows:

$fruits = array("apple", "banana", "orange");
unset($fruits[1]); // 删除数组中下标为1的元素 banana
print_r($fruits); // 输出: Array ( [0] => apple [2] => orange )

This function is very suitable for deleting the element with a specified subscript, and there is no need to access the value of the element after deletion.

4. array_splice() function

array_splice() function is used to delete the specified elements in the array and replace the deleted elements with new elements. The sample code is as follows:

$fruits = array("apple", "banana", "orange");
array_splice($fruits, 1, 1); // 从数组中删除下标为1的元素 banana
print_r($fruits); // 输出: Array ( [0] => apple [1] => orange )

This function is very suitable for deleting elements with a specified subscript and needs to be replaced with new elements after deletion.

The above is how to use array functions to delete elements in an array. Next we will introduce the method of using loop traversal to delete the elements that have been taken out of the array.

2. Delete the retrieved array elements

When looping through the array, it is a good choice to use the unset() function to delete the retrieved elements. The sample code is as follows:

$fruits = array("apple", "banana", "orange");
foreach ($fruits as $key => $value) {
    echo $value;
    unset($fruits[$key]); // 删除已取出的元素
    print_r($fruits); // 输出: Array ( [1] => banana [2] => orange )
}

In the above code, we use a foreach loop to traverse the array, take out the values ​​of the array elements and output them. At the same time, use the unset() function to delete the elements that have been taken out. For reference, we also call the print_r() function to output the array with elements removed after each loop. As you can see, as the loop proceeds, the elements that have been taken out of the array are deleted.

3. Method Selection

Up to this point, you have learned how to delete array elements in PHP and how to delete the elements that have been taken out. In practical applications, the appropriate method should be selected according to the scenario.

• If you need to delete the first element or the last element in the array, you can use the array_shift() or array_pop() function.
• If you need to delete the element with a specified subscript and need to access the value of the element after deletion, you can use the unset() function.
• If you need to delete the element with a specified subscript and replace it with a new element after deletion, you can use the array_splice() function.
• If you are traversing an array and need to delete the elements that have been taken out during the traversal, you can use the unset() function.

In short, for different application scenarios, these methods should be used flexibly and the most appropriate method should be selected to achieve the needs.

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