How to remove the first value of an array in php

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;

## If
• # is 0, then delete it starting from the first element; if

• is a negative number, then start from the position

  -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:

• is a positive number, then it means deleting length elements;

• is a negative number, then all elements starting from start and ending with length counting down from the end of the array will be deleted;

• If it is omitted, then all elements starting from start will be deleted until the end of the array. of all elements.

<?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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