Two methods: 1. Use array_unshift() to add one or more elements to the header, the syntax is "array_unshift(array, value 1, value 2...)"; 2. Use array_splice( ), syntax "array_splice(array,0,0,single value or array)".
The operating environment of this tutorial: Windows 7 system, PHP version 8.1, DELL G3 computer
php is in the array header Methods to add elements from the bottom
1. Use the array_unshift() function
The array_unshift() function can insert one or more elements at the beginning of the array New element (key value).
array_unshift($array,$value1,$value2...)
Let’s take a closer look at the following example:
<?php $arr=array(10,12,20); array_unshift($arr,8,"9"); var_dump($arr); ?>
array_unshift($arr,8,9)
It can be seen that it is inserted at the beginning of the $arr array Two new elements: the numerical value "8
" and the string "9
", so the output result is:
array_unshift( ) function will not maintain the original numerical index relationship, but will delete all numerical key names and reassign them, that is, count again from 0; but all string key names will remain unchanged.
<?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. Use array_splice() function
array_splice() function is a A powerful function that can be used to delete array elements, replace array elements, and insert array elements (just set the parameter $length to 0).
array_splice($array,$start,$length,$value)
When $length=0
, then the parameter $start
can specify the position (subscript) to start inserting, and the parameter $value
You can specify the insertion value (if there are multiple values, you need to set it as an array).
If you want to add elements at the beginning, the value of $start needs to be 0.
<?php header("Content-type:text/html;charset=utf-8"); $arr1=array(10,12,20); var_dump($arr1); 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); ?>
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求和方法:1、用array_column()获取多维数组中指定一列的全部元素,语法“rray_column(数组, '指定列名')”,会返回一个包含全部元素的结果数组;2、用“array_sum(结果数组)”计算结果数组中所有元素的和即可。

增加元素的方法:1、使用array_push()函数,语法“array_push(二维数组,值1,值2...);”;2、使用array_splice()函数,语法“array_splice(二维数组,count(二维数组),0,元素值)”。

获取方法:1、用“array_values(数组)”将指定数组转为索引数组;2、用“array_search(数值,索引数组)”,在索引数组中搜索数值,返回对应的索引值(下标);3、用“索引值+1”语句获取元素在数组中的位置值。

php数组里面可以放数组。PHP数组可以存储所有类型的数据,当然也包括数组本身;如果一个数组中的元素是另一个数组,就构成了包含数组的数组,即多维度数组。数组的不同维度标志着需用几个下标(索引)来获取对应的数组元素,比如二维数组需用两个下标。

方法:1、循环遍历数组,语法“foreach($arr as $k=>$v){}”;2、循环体中,用“==”判断元素值是否为null,如果是则用unset()删除该元素,语法“if($v==null){unset($arr[$k]);}”。

php中只比较值的数组交集函数是“array_intersect()”;该函数用于比较两个(或更多个)数组的键值,语法“array_intersect(数组1,数组2...)”,会返回一个交集数组,所包含的值是从被比较的数组(数组1)中取。

去掉方法:1、用“sort($arr)”对数组进行升序排序,排序后该数组的第一个元素就是最小值,最后一个元素就是最大值;2、用“array_pop($arr)”删除最后一个元素,用“array_shift($arr)”删除第一个元素即可。

php中可用preg_match_all()配合正则表达式过滤字符串,只获取中文字符;语法“preg_match_all("/[\x{4e00}-\x{9fff}]+/u","$str",$arr);”,会将匹配字符存入“$arr”数组中。


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