PHP循环结合数组和list的使用
foreach的使用:1.用法1
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif<?php
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif $arr=array("张三","李四","王五","马六");
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif foreach($arr as$value)
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif echo $value.'<br/>';
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif?>
2.用法2
<?php
$arr=array('chinese'=>130,'math'=>140,'english'=>135,'computer'=>130);
foreach($arr as $key=>$value)
echo $key.':'.$value.'<br/>';
?>
3.按拷贝还是引用
默认按拷贝，和函数很相似:
<?php
$arr=array(1,2,3,4);
foreach($arr as $value)
$value*=2;//其实改变的是副本对原数组没有影响
print_r($arr);//Array ( => 1 => 2 => 3 => 4 )
?>
但是可以改成引用方式,通过&符号:
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif<?php
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif $arr=array(1,2,3,4);
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif foreach($arr as&$value)
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif $value*=2;
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif print_r($arr);//Array ( => 2 => 4 => 6 => 8 )
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif?>
4.for循环
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif<?php
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif$arr=array(1,2,3,4,5);
http://xcf007.blog.iyunv.com/images/editer/InBlock.giffor($i=0;$i<count($arr);$i++)
http://xcf007.blog.iyunv.com/images/editer/InBlock.gifecho $arr[$i].'<br/>';
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif?>
5.each/list
each用法,每次取出个4元素数组，其中0,key对应键;1,value对应值:
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif<?php
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif$arr = array("张三", "李四", "王五");
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif$bar = each($arr);
http://xcf007.blog.iyunv.com/images/editer/InBlock.gifprint_r($bar);//Array ( => 张三 => 张三 => 0 => 0 )
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif?>
list的用法:
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif<?php
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif$arr = array("张三", "李四", "王五");
http://xcf007.blog.iyunv.com/images/editer/InBlock.giflist($a, $a, $a) = $arr;
http://xcf007.blog.iyunv.com/images/editer/InBlock.gifprint_r($a);//Array ( => 王五 => 李四 => 张三 )
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif?>
list结合each使用:
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif<?php
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif$arr = array("张三"=>20, "李四"=>29, "王五"=>23);
http://xcf007.blog.iyunv.com/images/editer/InBlock.gifwhile(list($key, $value) = each($arr))
http://xcf007.blog.iyunv.com/images/editer/InBlock.gifecho "$key=>$value".'<br/>';
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif?>
注意while(list($key, $value) = each($arr))中each得到的4元素数组中有2个数字索引分别赋给list中2个变量。
所以
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif<?php
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif$arr = array("张三",'b'=>"李四", "王五");
http://xcf007.blog.iyunv.com/images/editer/InBlock.giflist($a, $a) = $arr;
http://xcf007.blog.iyunv.com/images/editer/InBlock.gifprint_r($a);//Array ( => 王五 => 张三 )
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif?>
6.多维数组
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif<?php
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif$a = array();
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif$a['山东'] = "济南";
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif$a['山东'] = "威海";
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif$a['黑龙江'] = "哈尔滨";
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif$a['黑龙江'] = "齐齐哈尔";
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif
foreach($a as$key1=>$v1) {
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif echo "<b>$key1</b>".'<br/>';
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif foreach($v1 as$v2) {
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif echo "$v2 \n";
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif }
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif echo '<br/>';
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif}
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif?>
7.数组函数
key取键值
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif<?php
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif$arr = array(
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif '张三' => '济南',
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif '李四' => '烟台',
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif '王五' => '威海',
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif '赵六' => '北京',
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif );
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif
while($person = current($arr)) {
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif if($person == '威海') {
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif echo key($arr).'<br />';
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif }
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif next($arr);
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif}
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif?>
上面会得到 '王五',但是如果烟台为 ""空串，则程序执行到这里会跳出循环，空串转成false。
用for实现foreach效果:
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif<?php
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif$arr = array(
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif '百度' => 'http://www.baidu.com',
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif '谷歌' => 'http://www.google.com.hk',
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif '400电话' => 'http://www.my400800.cn',
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif 'bing' => 'http://cn.bing.com',
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif );
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif
for(reset($arr);$key=key($arr);next($arr))
http://xcf007.blog.iyunv.com/images/editer/InBlock.gifecho $key.'<br/>';
http://xcf007.blog.iyunv.com/images/editer/InBlock.gif?>
这个问题同上，如果某个键值计算为false也会跳出循环。
页:
[1]