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Two deletion methods: 1. Use the array_shift() function to delete the first value of the array. The syntax "array_shift($arr)" will return the deleted element. 2. Use the array_splice() function to delete the first value, the syntax is "array_splice($arr,0,1);"; the second and third parameters of this function can be negative numbers.
The operating environment of this tutorial: windows7 system, PHP8.1 version, DELL G3 computer
php removes the array number Two methods for a value
Method 1: Use array_shift() function to delete
array_shift() function is used to delete elements in an array The first element and returns the removed element.
array_shift($arr)
array_shift() function After deleting the first element at the beginning of the $arr array, the length of the arr array will be reduced by 1 and all other elements will be moved forward by one. If the key is numeric, all elements will get a new key, starting at 0 and increasing by 1; but string keys will remain unchanged.
Note: This function will change the original array
<?php header("Content-type:text/html;charset=utf-8"); $arr=array(10,12,20,25,24); echo "原数组:"; var_dump($arr); array_shift($arr); echo "删除后的数组:" ; var_dump($arr); ?>
You can see this example, there are 5 elements in our original $arr array , after using the array_shift($arr) method, re-use var_dump($arr) to output the array, and found that there are only 4 elements, and the head element of the array has been deleted.
Method 2: Use the array_splice() function to delete
The array_splice() function is a powerful function with multiple functions: it can insert array elements and replace array elements. , of course, you can also delete array elements (after all, the job of the array_splice() function is to delete the specified element and replace it with other values). Let’s take a look at its deletion function.
Let’s look at a small example below.
<?php header("Content-type:text/html;charset=utf-8"); $arr=array(10,12,20,25,24); echo "原数组:"; var_dump($arr); echo "删除后的数组:" ; array_splice($arr,0,1); var_dump($arr); ?>
The output result is:
It can be seen that we use array_splice($arr,0,1)
from $arr Start deleting elements from the first element of the array and delete 1 element. array_splice($arr,$start,$length)
will delete $length elements starting from the $start position.
The $start parameter has three values:
is a positive number, then start from the $start position and delete later;
-start from the end of $arr Start by deleting from the back to the front. For example -2 means start from the second to last element of the array.
<?php header("Content-type:text/html;charset=utf-8"); $arr=array(10,12,20,25,24); echo "原数组:"; var_dump($arr); echo "删除后的数组:" ; array_splice($arr,-2); var_dump($arr); ?>The output result is:
<?php header("Content-type:text/html;charset=utf-8"); $arr=array(10,12,20,25,24); echo "原数组:"; var_dump($arr); echo "删除后的数组:" ; array_splice($arr,2,2); var_dump($arr); ?>The output result is: In the operation of deleting elements, the $length parameter also has three values:
<?php header("Content-type:text/html;charset=utf-8"); $arr=array(10,12,20,25,24); echo "原数组:"; var_dump($arr); echo "删除后的数组:" ; array_splice($arr,2,-1); var_dump($arr); ?>The output result is:
$lengthThe parameter can also be 0, which means no To delete an element, you can combine it with the fourth parameter $value of the function to perform an insertion operation (I will not give a detailed introduction here).
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