php中substr()函数参数说明及用法实例_PHP
本文实例讲述了php中substr()函数参数说明及用法。分享给大家供大家参考。具体如下:
string substr(string $string ,int $start [, int $length ]),它可以用于在一个较长的字符串中查找匹配的字符串或字符,$string为所要处理的字符串,$start为开始选取的位置,$length为要选取的长度.
$length 为正数据从左向右读取字符.
$length 为负数时就右向左读取字符.
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.
charlist 可选,规定要返回的字符串长度,默认是直到字符串的结尾.
正数 - 在字符串的指定位置开始
负数 - 在从字符串结尾的指定位置开始
0 - 在字符串中的第一个字符处开始
PHP实例代码如下:
代码如下:
$rest_1 = substr("abcdef", 2); // returns "cdef"
$rest_2 = substr("abcdef", -2); // returns "ef"
$rest1 = substr("abcdef", 0, 0); // returns ""
$rest2 = substr("abcdef", 0, 2); // returns "ab"
$rest3 = substr("abcdef", 0, -1); // returns "abcde"
$rest4 = substr("abcdef", 2,0); // returns ""
$rest5 = substr("abcdef", 2,2); // returns "cd"
$rest6 = substr("abcdef", 2, -1); // returns "cde"
$rest7 = substr("abcdef", -2,0); // returns ""
$rest8 = substr("abcdef", -2,2); // returns "ef"
$rest9 = substr("abcdef", -2,-1); // returns "e"
希望本文所述对大家的PHP程序设计有所帮助。

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