search
HomeBackend DevelopmentPHP ProblemHow to add elements to the head of an array in php

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)".

How to add elements to the head of an array in php

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:

How to add elements to the head of an array in php

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:

How to add elements to the head of an array in php

#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);
?>

How to add elements to the head of an array in php

Recommended learning: "PHP Video Tutorial"

The above is the detailed content of How to add elements to the head of an array in php. For more information, please follow other related articles on the PHP Chinese website!

Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
php怎么对多维数组的某一列求和php怎么对多维数组的某一列求和May 09, 2022 pm 05:55 PM

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。

php怎么在二维数组末尾增加元素php怎么在二维数组末尾增加元素Apr 26, 2022 pm 06:29 PM

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)”。

php怎么获取数值在数组中的哪个位置php怎么获取数值在数组中的哪个位置May 07, 2022 pm 09:03 PM

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数组里面可放数组吗php数组里面可放数组吗May 10, 2022 pm 01:48 PM

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。

php数组怎么去掉null值php数组怎么去掉null值May 07, 2022 pm 08:35 PM

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什么php中只比较值的数组交集函数是什么Apr 29, 2022 pm 02:41 PM

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。

php数组怎么去掉最大和最小元素php数组怎么去掉最大和最小元素May 09, 2022 pm 08:47 PM

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怎么只获取中文字符php怎么只获取中文字符Apr 28, 2022 pm 08:15 PM

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。

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

AI Hentai Generator

AI Hentai Generator

Generate AI Hentai for free.

Hot Tools

mPDF

mPDF

mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SAP NetWeaver Server Adapter for Eclipse

SAP NetWeaver Server Adapter for Eclipse

Integrate Eclipse with SAP NetWeaver application server.

VSCode Windows 64-bit Download

VSCode Windows 64-bit Download

A free and powerful IDE editor launched by Microsoft

DVWA

DVWA

Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software