# 第二课 数组
> 声名数组两种写法
```
<pre class="calibre14">```
$arr <span class="token">=</span> <span class="token1">array</span><span class="token2">(</span><span class="token3">1</span><span class="token2">,</span><span class="token3">2</span><span class="token2">,</span><span class="token3">3</span><span class="token2">)</span><span class="token2">;</span>
$arr1<span class="token2">[</span><span class="token3">1</span><span class="token2">]</span><span class="token">=</span><span class="token4">'a'</span><span class="token2">;</span>
$arr1<span class="token2">[</span><span class="token3">2</span><span class="token2">]</span><span class="token">=</span><span class="token4">'b'</span><span class="token2">;</span>
```
```
> 遍历数组
```
<pre class="calibre14">```
$arr <span class="token">=</span> <span class="token1">array</span><span class="token2">(</span><span class="token4">'a'</span><span class="token">=</span><span class="token">></span><span class="token3">1</span><span class="token2">,</span><span class="token4">'b'</span><span class="token">=</span><span class="token">></span><span class="token3">2</span><span class="token2">)</span><span class="token2">;</span>
<span class="token1">foreach</span><span class="token2">(</span>$arr as $k<span class="token">=</span><span class="token">></span>$v<span class="token2">)</span><span class="token2">{</span>
echo $k<span class="token2">.</span><span class="token4">":"</span><span class="token2">.</span>$v<span class="token2">.</span><span class="token4">"\n"</span><span class="token2">;</span>
<span class="token2">}</span>
<span class="token5">while</span><span class="token2">(</span><span class="token1">list</span><span class="token2">(</span>$k<span class="token2">,</span>$v<span class="token2">)</span><span class="token">=</span><span class="token1">each</span><span class="token2">(</span>$arr<span class="token2">)</span><span class="token2">)</span><span class="token2">{</span>
echo $k<span class="token2">.</span><span class="token4">":"</span><span class="token2">.</span>$v<span class="token2">.</span><span class="token4">"\n"</span><span class="token2">;</span>
<span class="token2">}</span>
```
```
- \[x\]字符数组转换
```
<pre class="calibre14">```
<span class="token1">explode</span><span class="token2">(</span><span class="token4">'-'</span><span class="token2">,</span><span class="token4">'1-2-3-4'</span><span class="token2">)</span><span class="token2">;</span><span class="token6">//分割成数组</span>
<span class="token1">implode</span><span class="token2">(</span><span class="token4">'-'</span><span class="token2">,</span>$arr<span class="token2">)</span><span class="token2">;</span><span class="token6">//转换成字符串</span>
```
```
> 元素个数 count($arr)
- \[\] 查找元素,返回下标
```
<pre class="calibre14">```
$str <span class="token">=</span> <span class="token1">array_search</span><span class="token2">(</span><span class="token4">'1'</span><span class="token2">,</span><span class="token1">array</span><span class="token2">(</span><span class="token4">'k'</span><span class="token">=</span><span class="token">></span><span class="token3">1</span><span class="token2">,</span><span class="token4">'f'</span><span class="token">=</span><span class="token">></span><span class="token3">2</span><span class="token2">)</span><span class="token2">)</span><span class="token2">;</span>
```
```
> 合并数组
`$result = array_merge($array1, $array2);`
> 返回键名
```
<pre class="calibre16">```
$arr <span class="token">=</span> <span class="token1">array_keys</span><span class="token2">(</span>$array<span class="token2">)</span><span class="token2">)</span><span class="token2">;</span>
$str <span class="token">=</span> <span class="token1">array_pop</span><span class="token2">(</span>$arr<span class="token2">)</span><span class="token2">;</span>取出最后一个<span class="token2">,</span>返回的单个元素<span class="token2">,</span>原数组少一个
$str <span class="token">=</span> <span class="token1">array_shift</span><span class="token2">(</span>$arr<span class="token2">)</span><span class="token2">;</span> 取出第一个
<span class="token1">array_push</span><span class="token2">(</span>$arr<span class="token2">,</span> <span class="token4">"apple"</span><span class="token2">,</span> <span class="token4">"raspberry"</span><span class="token2">)</span><span class="token2">;</span> 压入末尾元素
$k <span class="token">=</span> <span class="token1">array_rand</span><span class="token2">(</span>$arr<span class="token2">,</span> <span class="token3">2</span><span class="token2">)</span> 随机取出<span class="token3">2</span>个元素<span class="token2">,</span>返回下标
$result <span class="token">=</span> <span class="token1">array_reverse</span><span class="token2">(</span>$arr<span class="token2">)</span><span class="token2">;</span> 反序
$arr <span class="token">=</span> <span class="token1">array_slice</span><span class="token2">(</span>$input<span class="token2">,</span> <span class="token">-</span><span class="token3">2</span><span class="token2">,</span> <span class="token3">1</span><span class="token2">)</span><span class="token2">;</span> 从某个位置开始<span class="token2">,</span>取出元素个数<span class="token2">,</span>负数从末尾开始<span class="token2">,</span>不填写到末尾
<span class="token1">array_sum</span><span class="token2">(</span>$a<span class="token2">)</span>数值之和
<span class="token1">array_unique</span><span class="token2">(</span>$input<span class="token2">)</span> 去掉重复
<span class="token1">array_unshift</span><span class="token2">(</span>$queue<span class="token2">,</span> <span class="token4">"apple"</span><span class="token2">,</span> <span class="token4">"raspberry"</span><span class="token2">)</span><span class="token2">;</span>开头插入
$arr <span class="token">=</span> <span class="token1">array_values</span><span class="token2">(</span>$array<span class="token2">)</span> 返回值组成的数组
<span class="token1">count</span><span class="token2">(</span>$arr<span class="token2">)</span>计算数组个数
<span class="token1">in_array</span><span class="token2">(</span><span class="token4">"Irix"</span><span class="token2">,</span> $arr<span class="token2">)</span><span class="token2">)</span> 元素是否在数组中
<span class="token1">range</span><span class="token2">(</span><span class="token3">0</span><span class="token2">,</span> <span class="token3">100</span><span class="token2">,</span> <span class="token3">10</span><span class="token2">)</span> <span class="token3">0</span><span class="token">-</span><span class="token3">100</span> 步长<span class="token3">10</span>的数组
$k <span class="token">=</span> <span class="token1">range</span><span class="token2">(</span><span class="token4">'a'</span><span class="token2">,</span><span class="token4">'z'</span><span class="token2">)</span><span class="token2">;</span>
<span class="token1">shuffle</span><span class="token2">(</span>$arr<span class="token2">)</span><span class="token2">;</span> 打乱数组
```
```
- 简介
- 第一章 数据库
- Mysql/mariadb
- 函数
- 基础
- 增删改索引
- 标准查询
- 高级查询
- TIDB集群mysql解决方案
- Redis
- 语言基础
- 5种数据类型
- 其他类型
- Sqlite
- 语言基础
- 常用查询
- 第二章 PHP
- 语言基础
- 第一课 流程控制和运算
- 第二课 数组
- 第三课 日期时间
- 第四课 常用函数
- 第五课 字符串
- 第六课 文件操作
- 第七课 面向对象
- 第八课 正则表达式
- 第九课 图片处理生成
- 第十课 curl/memche
- 第十一课 mysql和pdo
- 第十三课 cookie和session
- 第十四课 xml操作
- 第十五课 php5.3+新特性
- 第十六课 php7+
- 第十七课 密码安全
- 废弃函数
- php命令行
- redis应用
- 算法
- 排序算法
- 基础算法
- 无限级分类
- 自定义函数Fn
- 查找算法
- 自定义函数数据函数fn
- laravel
- 路由
- 常用语句
- 数据库
- dingo/api
- Yii2
- 控制器
- 常用类
- 数据库
- redis
- thinkphp6
- TP6文档
- TP6插件
- dedecms
- 织梦标签大全
- 数据库操作
- 内置函数和定义函数
- 织梦核心改动
- 织梦插件/底层标签开发
- PHP相关工具
- composer
- php开发环境phpenv
- Phpstorm使用
- windows编译php扩展
- PHP开源库
- 开源项目管理禅道
- sns_auth
- php-casbin权限控制
- php-jwt
- 微信SDKeasywechat
- querylist采集库
- workerman
- Box/Spout处理excel和csv
- dll扩展
- redis/memche/xdebug
- redis
- Lua
- php_xlswriter
- event
- swoole
- 常用代码库
- 微擎框架
- 第一课全局变量
- 第二课常用函数
- 第三课自定义微擎独有函数
- 第四课数据库操作
- 第五课微信端回复
- 第六课微擎高级操作
- 第八课global函数列表
- mainfest.xml详解
- js方法
- 人人商城
- 第一课model解读
- 第二课常用语句解读
- 第三课常用js解读
- 第四课附录常见问题
- 第五课附录处理报表|支付
- 常用JSON状态码
- 第三章 JavaScript
- js基础
- 浏览器对象
- 语言基础
- html5接口
- ES6新语法
- vue
- 基础语法
- 京东vueUI组件
- uniapp
- 组件开发规范
- nodejs
- 基础知识
- 安装node
- nvm不同版本node切换
- js常用标准库
- zepto/jquery
- weui
- js图标库
- elementUI
- validator表单验证
- layer弹出层
- requirejs
- wow动画
- 动画animate
- swiper4
- 百度编辑器
- flyio/axios/qs
- jquery.form
- bootstrap3
- clipboard复制
- slideout侧滑
- imagehover.css图片悬停动画
- webpack打包
- Bulma UI框架
- store 客户端存储
- lottie动画创建库
- sweetalert
- js自定义函数
- 常见JSSDK
- 微信公众号JSSDK
- 腾讯地图jssdk
- 微信小程序
- 第四章 编程语言
- markdown语言
- Dart语言
- Dart语言基础
- Flutter框架
- Lua语言
- 字符串,数组,表
- 自定义方法
- go语言
- 第1.1语言基本语法
- 第1.2流程控制
- 第1.3函数
- 第1.4结构体
- 第1.5接口
- 第1.6包
- go语言框架Gin
- CSS3语言
- CSS与CSS3
- 选择符
- 属性
- css3
- loading动画
- HTML5语言
- less
- sass
- C#
- 基础知识
- 函数
- 第五章 开发工具
- git
- nginx/apache服务器
- Linux常用操作
- crontab定时任务
- 注册表与cmd
- 阿里云ECS
- frp穿透和ssl续期
- 宝塔安装
- 树莓派
- 浏览器模拟
- 火狐/chrome常用插件
- WSL安装使用
- mac brew和终端命令
- win10相关