PHP substr()函数与示例
PHPsubstr()方法
substr()函数是PHP中的字符串函数，用于从字符串的指定索引中获取子字符串。
语法：
substr(string, start, [length]);
这里，
字符串是主字符串。
start是字符串的起始索引，子字符串从该索引处返回。
length是一个可选参数，它定义要返回的字符数。
注意：负值指向字符串的末尾。例如：-1指向最后一个字符，-2指向倒数第二个字符，-3指向倒数第三个字符，依此类推...
例子：
Input:
str = "Hello friends how are your friends?";
start =10
Output:
"nds how are your friends?"
str = "Hello friends how are your friends?";
start =10
length = 5
Output:
"nds h"PHP代码：
<?php $str = "Hello friends how are your friends?"; //将子字符串从第10个索引返回到字符串的末尾 $substring = substr($str,10); echo ($substring . "\n"); //将子串从第10个索引返回到下一个5个字符 $substring = substr($str,10,5); echo ($substring . "\n"); //使用负值进行测试 $substring = substr($str,-1); echo ($substring . "\n"); //使用负值进行测试 $substring = substr($str,10,-1); echo ($substring . "\n"); //使用负值进行测试 $substring = substr($str,-5); echo ($substring . "\n"); //使用负值进行测试 $substring = substr($str,3,-5); echo ($substring . "\n"); ?>
输出结果
nds how are your friends? nds h ? nds how are your friends ends? lo friends how are your fri