数组是在程序设计中,为了处理方便, 把具有相同类型的若干变量按有序的形式组织起来的一种形式。这些按序排列的同类数据元素的集合称为数组。下面介绍PHP中的数组声明。
一、数组的概述
1.数组的本质:管理和操作一组变量,成批处理
2.数组时复合类型(可以存储多个)
3.数组中可以存储任意长度的数据,也可以存储任意类型的数据
4.数组可以完成其他语言数据结构的功能(链表,队列,栈,集合类)
二、数组的分类
数组中有多个单元,(单元称为元素)
每个元素(下标[键]和值)
单访问元素的时候,都是通过下标(键)来访问元素
1.一维数组,二维数组,三维数组。。。多维数组 (数组的数组,就是在数组中存有其他的数组)
2.PHP中有两种数组
索引数组:就是下标是顺序整数的索引
关联数组:就是下标是字符串作为索引
下标(整数,字符串)只有这两种
三、数组多种声明方式
1.直接为数组元素赋值声明
如果索引下标不给出,就会从0开始顺序索引
如果给出索引下标,下一个就会从最大的开始增1
如果后面出现前面的下标,如果是赋值就是为前面的元素重新赋值
混合声明时,索引和关联不互相影响(不影响索引下标的声明)
2.使用array()函数声明
默认是索引数组,如果为关联数组和索引数组指定下标,使用 键=>值,多个成员之间使用" , "分割
3.使用其他的函数声明
(1)索引数组
<ol class="dp-c"> <li class="alt"><span><span class="vars">$user</span><span>[0]=1;</span><span class="comment">//用户序号 </span><span> </span></span></li> <li> <span class="vars">$user</span><span>[1]=</span><span class="string">"zhangsan"</span><span>;</span><span class="comment">//用户名 </span><span> </span> </li> <li class="alt"> <span class="vars">$user</span><span>[2]=10;</span><span class="comment">//年龄 </span><span> </span> </li> <li> <span class="vars">$user</span><span>[3]=</span><span class="string">"nan"</span><span>;</span><span class="comment">//性别 </span><span> </span> </li> <li class="alt"> <span class="func">echo</span><span> </span><span class="string">'<pre class="brush:php;toolbar:false">';
(2)关联数组
<ol class="dp-c"> <li class="alt"><span><span></span></span></li> <li> <span class="vars">$user</span><span>[</span><span class="string">"id"</span><span>]=1; </span> </li> <li class="alt"> <span class="vars">$user</span><span>[</span><span class="string">"name"</span><span>]=</span><span class="string">"zhangsan"</span><span>; </span> </li> <li> <span class="vars">$user</span><span>[</span><span class="string">"age"</span><span>]=10; </span> </li> <li class="alt"> <span class="vars">$user</span><span>[</span><span class="string">"sex"</span><span>]; </span> </li> <li> <span class="vars">$user</span><span>[</span><span class="string">"age"</span><span>]=90;</span><span class="comment">//赋值 </span><span> </span> </li> <li class="alt"> <span class="func">echo</span><span> </span><span class="vars">$user</span><span>[</span><span class="string">"name"</span><span>];</span><span class="comment">//输出 </span><span> </span> </li> <li> <span class="comment">//使用array()声明数组 </span><span> </span> </li> <li class="alt"> <span class="vars">$user</span><span>=</span><span class="keyword">array</span><span>(1,</span><span class="string">"zhangsan"</span><span>,10,</span><span class="string">"nan"</span><span>); </span> </li> <li> <span class="comment">//使用array()声明关联数组 </span><span> </span> </li> <li class="alt"> <span class="vars">$user</span><span>=</span><span class="keyword">array</span><span>(</span><span class="string">"id"</span><span>=>1,</span><span class="string">"name"</span><span>=></span><span class="string">"zhangsan"</span><span>,</span><span class="string">"age"</span><span>=>10,</span><span class="string">"sex"</span><span>=></span><span class="string">"nan"</span><span>); </span> </li> <li> <span class="comment">//声明多维数组(多条记录),来保存一个表中的多条用户信息记录 </span><span> </span> </li> <li class="alt"> <span class="vars">$user</span><span>=</span><span class="keyword">array</span><span>( </span> </li> <li> <span class="comment">//用$user[0]调用这一行,比如调用这条记录中的姓名,$user[0][1] </span><span> </span> </li> <li class="alt"> <span class="keyword">array</span><span>(1,</span><span class="string">"zhangsan"</span><span>,10,</span><span class="string">"nan"</span><span>), </span> </li> <li> <span class="comment">//用$user[1]调用这一行,比如调用这条记录中的姓名,$user[1][1] </span><span> </span> </li> <li class="alt"> <span class="keyword">array</span><span>(2,</span><span class="string">"lisi"</span><span>,20,</span><span class="string">"nv"</span><span>) </span> </li> <li><span>); </span></li> <li class="alt"> <span class="comment">//数组保存多个表,每个表有多条记录 </span><span> </span> </li> <li> <span class="vars">$info</span><span>=</span><span class="keyword">array</span><span>( </span> </li> <li class="alt"> <span class="string">"user"</span><span>=></span><span class="keyword">array</span><span>( </span> </li> <li> <span class="keyword">array</span><span>(1,</span><span class="string">"zhangsan"</span><span>,10,</span><span class="string">"nan"</span><span>), </span> </li> <li class="alt"> <span class="keyword">array</span><span>(2,</span><span class="string">"lisi"</span><span>,20,</span><span class="string">"nv"</span><span>) </span> </li> <li><span>), </span></li> <li class="alt"> <span class="string">"score"</span><span>=></span><span class="keyword">array</span><span>( </span> </li> <li> <span class="keyword">array</span><span>(1,90,80,70), </span> </li> <li class="alt"> <span class="keyword">array</span><span>(2,60,40,70) </span> </li> <li><span>) </span></li> <li class="alt"><span>); </span></li> <li> <span class="func">echo</span><span> </span><span class="vars">$info</span><span>[</span><span class="string">"score"</span><span>][1][1];</span><span class="comment">//输出60, </span><span> </span> </li> <li class="alt"><span>?> </span></li> </ol>
希望通过本文的介绍,能给你带来帮助。