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

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

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

SublimeText3 English version

SublimeText3 English version

Recommended: Win version, supports code prompts!

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),

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

PhpStorm Mac version

PhpStorm Mac version

The latest (2018.2.1) professional PHP integrated development tool

VSCode Windows 64-bit Download

VSCode Windows 64-bit Download

A free and powerful IDE editor launched by Microsoft