PHP中substr()函数的解析(附代码详解)

113 阅读 0 评论 75 点赞

我是靠谱客的博主高兴海燕，这篇文章主要介绍PHP中substr()函数的解析(附代码详解)，现在分享给大家，希望可以做个参考。

在PHP的实战中，我们经常需要对URL字符串进行解析，截取我们所需要的片段，PHP为我们提供了substr()函数，我们可很轻松的获取我们所需要的数据，本文就带大家一起来看一看PHP中的substr()函数。

首先我们先看一看看substr()函数的语法:

复制代码substr ( string $string , int $start  , int $length = ? )1
substr ( string $string , int $start  , int $length = ? )
登录后复制

$string:需要截取的原字符串
$start:需要开始的索引位置（值可以为正整数、负整数、0）
$length:需要筛选的长度（值可以为正整数、负整数、0）若为空则默认截取至结束
返回值：经过截取得到的新字符串，若错误则返回false。

代码实例：

1.若参数都为非负整数

复制代码<?php
echo substr('uoften.com is all right', 1);   
echo "<br>";
echo substr('uoften.com is all right', 1, 3);  
echo "<br>";
echo substr('uoften.com is all right', 0, 4);
echo "<br>";  
echo substr('uoften.com is all right', 0, 8);
?>1
2
3
4
5
6
7
8
9
<?php
echo substr('uoften.com is all right', 1);   
echo "<br>";
echo substr('uoften.com is all right', 1, 3);  
echo "<br>";
echo substr('uoften.com is all right', 0, 4);
echo "<br>";  
echo substr('uoften.com is all right', 0, 8);
?>
登录后复制

复制代码输出：        hp.cn is all right
        hp.
        php.
        uoften.com i1
2
3
4
输出：        hp.cn is all right
        hp.
        php.
        uoften.com i
登录后复制

2.若$start出现负整数

复制代码<?php
echo substr("uoften.com is all right", -1);  
echo "<br>"; 
echo substr("uoften.com is all right", -2);  
echo "<br>"; 
echo substr("uoften.com is all right", -3, 1); 
?>1
2
3
4
5
6
7
<?php
echo substr("uoften.com is all right", -1);  
echo "<br>"; 
echo substr("uoften.com is all right", -2);  
echo "<br>"; 
echo substr("uoften.com is all right", -3, 1); 
?>
登录后复制

复制代码输出：
t
ht
g1
2
3
4
输出：
t
ht
g
登录后复制

3.若$length出现负整数

复制代码<?php
echo substr("uoften.com is all right", 0,-1);  
echo "<br>"; 
echo substr("uoften.com is all right",2, -1);  
echo "<br>"; 
echo substr("uoften.com is all right",4, 4); 
echo "<br>"; 
echo substr("uoften.com is all right",-3, -1); 
?>1
2
3
4
5
6
7
8
9
<?php
echo substr("uoften.com is all right", 0,-1);  
echo "<br>"; 
echo substr("uoften.com is all right",2, -1);  
echo "<br>"; 
echo substr("uoften.com is all right",4, 4); 
echo "<br>"; 
echo substr("uoften.com is all right",-3, -1); 
?>
登录后复制

复制代码输出：uoften.com is all righ
      p.cn is all righ
      cn i
      gh1
2
3
4
输出：uoften.com is all righ
      p.cn is all righ
      cn i
      gh
登录后复制

推荐：《2021年PHP面试题大汇总（收藏）》《php视频教程》

以上就是PHP中substr()函数的解析(附代码详解)的详细内容，更多请关注靠谱客其它相关文章！