Home > Article > Backend Development > How to add and delete elements to php array
Add method: 1. array_unshift() inserts elements at the beginning, the syntax is "array_unshift(array, element list)"; 2. array_push() inserts elements at the end, the syntax is "array_push(array, element)". Deletion method: 1. array_shift() deletes the first element, the syntax is "array_shift(array)"; 2. array_pop() deletes the last element, the syntax is "array_pop(array)".
The operating environment of this tutorial: windows7 system, PHP8.1 version, DELL G3 computer
php array adding elements Method
1. The array_unshift() function inserts new elements into the array
##array_unshift($array,$value1,$ value2...)The function can insert one or more new elements (key values) at the beginning of the array.
<?php $arr=array(10,12,20); array_unshift($arr,8,"9"); var_dump($arr); ?>
array_unshift($arr,8,9)It can be seen that two characters are inserted at the beginning of the $arr array new elements: the value "
8" and the string "
9", so the output result is:
<?php header("Content-type:text/html;charset=utf-8"); $arr=array("a"=>"red","b"=>"green",3=>"pink"); echo "原来的数组:"; var_dump($arr); array_unshift($arr,"blue"); echo "在开头插入一个新元素后:"; var_dump($arr); ?>Output result:
2. The array_push() function inserts new elements into the array
array_push($array,$value1,$value2...)The function can insert one or more elements (key values) at the end of the array.
<?php $arr=array(10,12,20); array_push($arr,8,"9",3.14); var_dump($arr); ?>
array_push($arr,8,"9",3.14)It can be seen that in the $arr array Insert 3 elements at the end: integer "
8", string "
9" and floating point number "
3.14", so the output result is:
<?php header("Content-type:text/html;charset=utf-8"); $arr=array("a"=>"red","b"=>"green",3=>"pink"); array_push($arr,8,"9",3.14); var_dump($arr); ?>Output result:
3. The array_pad() function inserts new elements into the array
array_pad($array,$size,$value)The function can insert a key value
$value into the array
$array, thereby filling the array to the specified The length of
$size. (The
$size parameter can be understood as the final number of elements in the array, that is, the length of the array after the insertion operation).
<?php $arr=array(10,12,20); $result =array_pad($arr,5,1); var_dump($result); ?>As can be seen from
array_pad($arr,5,1),
$size## The value of # is 5, then there are 5 elements in the array after the insertion operation; and there are 3 elements in the original array, then only 2 elements need to be inserted. And because the inserted value $value
is 1, you only need to insert 2 elements with the value "1". Therefore, the output result is:
As can be seen from the above example, the array_pad() function can insert elements at the end of the array. In fact, the array_pad() function can also insert elements at the end of the array. Insert elements at the beginning; and the key is the
parameter. The
parameter has three values: if
If
array, no element will be inserted. Insert operation.
<?php $arr=array(10,12,20); $result =array_pad($arr,-5,1); var_dump($result); $result =array_pad($arr,3,1); var_dump($result); $result =array_pad($arr,2,1); var_dump($result); ?>
The value of parameter
$value can also be an array, that is Insert an entire array, and the original array will become a two-dimensional array. <pre class="brush:php;toolbar:false"><?php
header("Content-type:text/html;charset=utf-8");
$arr=array(10,12,20);
$result =array_pad($arr,-5,array("张三",25,"男"));
var_dump($result);
?></pre>
The output result is:
array_splice($array,$start,$length,$value)
The function is a powerful function that can be used to delete array elements, replace array elements, and also insert array elements (just set the parameters $length
can be set to 0). When
, then the parameter $start
can specify the position (subscript) to start inserting, and the parameter $value
can The insertion value can be specified (if there are multiple values, it needs to be set as an array). Let’s take a closer look at the following example:
<?php header("Content-type:text/html;charset=utf-8"); $arr1=array(10,12,20); array_splice($arr1,0,0,"1"); var_dump($arr1); $arr2=array(10,12,20); array_splice($arr2,0,0,array("1",25,"3")); var_dump($arr2); ?>
The output result is:
从上例可以看出,当$start=0
时,会将$value值按顺序的插入到数组开头。那么想要在数组末尾插入元素要怎么弄?
简单,将$start
的值设置为“数组长度值”,即count($arr)
即可。
<?php header("Content-type:text/html;charset=utf-8"); $arr1=array(10,12,20); array_splice($arr1,count($arr1),0,"1"); var_dump($arr1); $arr2=array(10,12,20); array_splice($arr2,count($arr2),0,array("1",25,"3")); var_dump($arr2); ?>
输出结果为:
php数组删除元素的方法
1、array_shift()函数删除第一个元素
array_shift() 函数用于删除数组中的第一个元素,并返回被删除的元素。
注释:如果键名是数字的,所有元素都将获得新的键名,从 0 开始,并以 1 递增
<?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); ?>
2、array_pop()函数删除最后一个元素
array_pop() 函数删除数组中的最后一个元素。
<?php header("Content-type:text/html;charset=utf-8"); $arr=array(10,12,20,25,24); echo "原数组:"; var_dump($arr); array_pop($arr); echo "删除后的数组:" ; var_dump($arr); ?>
3、array_unique()函数移除重复元素
array_unique() 函数用于移除数组中重复的值。如果两个或更多个数组值相同,只保留第一个值,其他的值被移除。
注释:被保留的数组将保持第一个数组项的键名类型。
array_unique(array,sortingtype)
参数 | 描述 |
---|---|
array | 必需。规定数组。 |
sortingtype | 可选。规定排序类型。可能的值:
|
<?php header("Content-type:text/html;charset=utf-8"); $arr=array(1,2,3,4,4,2,6); echo "原数组:"; var_dump($arr); echo "删除重复值后:" ; var_dump(array_unique($arr)); ?>
4、array_splice()函数删除任意位置元素
array_splice()是一个强大的函数,有多重功能:可以插入数组元素、可以替换数组元素,当然也可以删除数组元素(毕竟array_splice()函数的本职工作是删除指定元素并用其它值取代)。
array_splice()函数可以从指定位置开始删除指定个数的元素。
array_splice($arr,$start)
会删除从$start位置开始的所有元素删除。
<?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); ?>
$start参数有三种取值情况:
为正数,那么从$start位置开始,往后删除;
为0,那么从第一个元素开始,往后删除;
为负数,则从距离 $arr 末端 -start 的位置开始,从后往前删除。例如 -2 意味着从数组的倒数第二个元素开始。
<?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); ?>
array_splice()函数是强大的,可以删除多个元素,也可只删除一个元素,那就需要给该函数指定一个$length参数(第三个参数),该参数用来规定删除的元素个数。
<?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); ?>
$length参数也有三种取值情况:
为正数,那么就表示删除 length 个元素;
为负数,那么将删除从 start 开始,到数组末尾倒数 length 为止的所有元素;
如果省略,那么将删除从 start 开始,一直到数组末尾的所有元素。
<?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); ?>
$length参数还可以为0,那么就表示不删除元素,可以和该函数的第四个参数$value相配合,进行插入操作(这里就不做具体介绍了)。
5、unset()函数删除指定下标元素
unset()函数可以删除指定下标(键名)的一个数组元素
<?php header('content-type:text/html;charset=utf-8'); $arr = array(0 => "a", 1 => "b", 2 => "c"); echo "原数组:"; var_dump($arr); echo "删除后的数组:" ; unset($arr[1]); //↑ 你想删除的key var_dump($arr); ?>
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