PHP数组详解

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作为一名C++程序员，在转做PHP开发的过程中，对PHP数组产生了一些混淆，与C++数组有相似的地方，也有一些不同，下面就全面地分析一下PHP的数组及其与C++中相应数据类型的区别和联系。

数组的分类：

1、数值数组：也叫索引数组，即以数字（从0 开始）作为数组下标。相当于C++中的vector。

2、关联数组：以字符串作为数组下标。相当于C++中的map。

3、多维数组：数组中每个元素也是一个数组。其子数组中的每个元素也可以是数组。

数组的声明：

1、数值数组

a、如下例子中，会自动分配数字ID键。$names = array("Peter","Joe","Lily");b、如下例子中，我们人工分配数字ID键。$names[0] = "Peter";$names[1] = "Joe";$names[2] = "Lily";可以在脚本中使用这些ID键：<?php$names[0] = "Peter";$names[1] = "Joe";$names[2] = "Lily";echo $names[0]." and ".$names[1]." are ".$names[2]."'s neighbors";?>

2、关联数组：

例子1$ages = array("Peter"=>32, "Joe"=>30, "Lily"=>28);例子2本例与例子1相同，只是另一种创建数组的方法。$ages["Peter"] = "32";$ages["Joe"] = "30";$ages["Lily"] = "28";在脚本中使用关联数组：<?php$ages["Peter"] = "32";$ages["Joe"] = "30";$ages["Lily"] = "28";echo "Peter is ".$ages["Peter"]." years old.";?>以上脚本输出：Peter is 32 years old.

3、多维数组：

在本例中，我们创建了一个带有自动分配数字ID键的多维数组：$families = array{"Griffin"=>array{"Peter","Lois","Megan"},"Quagmire"=>array{"Glenn"},"Brown"=>array{"Cleveland","Loretta","Junior"}};echo "Is " . $families['Griffin'][2] . " a part of the Griffin family?";以上代码输出：Is Megan a part of the Griffin family?

数组遍历

1、for循环遍历for循环只能遍历索引数组。<?php$names = array("Peter","Joe","Lily");for($id=0;$id<count($names);++$id){echo $names[$id];}?>2、foreach遍历即可以遍历索引数组，也可以遍历关联数组遍历索引数组foreach(array_expression as $value){循环体;}遍历关联数组foreach(array_expression as $key=>$value){循环体;}A、一维数组遍历索引数组<?php$contact = array("李某","xx公司","abc@xx.com");foreach($contact as $value){echo $value;}?><?php$contact = array("姓名"=>"李某","公司"=>"xx公司","邮箱"=>"abc@xx.com");foreach($contact as $key=>$value){echo $key.":".$value;}?>B、多维数组遍历<?php$wage = array("市场部"=array(array(1,"李某","市场经理",8000),array(2,"王某","市场专员",5000),array(3,"刘某","市场专员",7000)),"产品部"=array(array(1,"李某","产品经理",9000),array(2,"王某","产品专员",6000),array(3,"刘某","产品专员",5000)),"账务部"=array(array(1,"李某","账务经理",7000),array(2,"王某","账务专员",6000),array(3,"刘某","账务专员",5000)));foreach($wage as $section=>$table){echo $section."部门人员如下";foreach($table as $row){foreach($row as $value){echo $value;}}}?>

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