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PHP中substr函数字符串截取用法分析,phpsubstr
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PHP中substr函数字符串截取用法分析,phpsubstr

Jun 13, 2016 am 08:48 AM
php substr

PHP中substr函数字符串截取用法分析,phpsubstr

本文实例讲述了PHP中substr函数字符串截取用法。分享给大家供大家参考,具体如下:

PHP中substr函数定义如下:

substr(string,start,length)

参数说明如下:

string 必需。规定要返回其中一部分的字符串。

start 
必需。规定在字符串的何处开始。
正数 - 在字符串的指定位置开始
负数 - 在从字符串结尾开始的指定位置开始
0 - 在字符串中的第一个字符处开始

length 

可选。规定被返回字符串的长度。默认是直到字符串的结尾。
正数 - 从 start 参数所在的位置返回的长度
负数 - 从字符串末端返回的长度

示例代码如下:

<&#63;php
 echo substr("Welcome to www.jb51.net!",0); //原样输出,不截取
 echo "<br>";
 echo substr("Welcome to www.jb51.net!",4,14); //从第4个字符开始连续截取14个字符
 echo "<br>";
 echo substr("Welcome to www.jb51.net!",-4,4); //从倒数第4个开始截取4个字符
 echo "<br>";
 echo substr("Welcome to www.jb51.net!",0,-4); //从第一个字符开始截取,截取到倒数第4个字符
&#63;>

Copy after login

运行结果如下:

Welcome to www.jb51.net!
ome to www.jb5
net!
Welcome to www.jb51.

Copy after login

希望本文所述对大家PHP程序设计有所帮助。

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