请问 以下 红色代码 preg_match('/[^a-z0-9_]/i', $act) 应该怎么理解呢? 麻烦会的朋友帮忙回复下,先谢啦
$act = Get('act');
if (!isset($act{0})){
$act = 'pa';
} elseif (preg_match('/[^a-z0-9_]/i', $act)){
exit;
}
回复讨论(解决方案)
/[^a-z0-9_]/i
匹配 字母、数字、下划线 以外的字符
preg_match('/[^a-z0-9_]/i', $act
preg_match 是php正则匹配方法
'/[^a-z0-9_]/i' 是匹配的正则表达式
$act 是用于检查匹配的字符串
正则表达式说明
a-z 表示匹配所有小写字母
0-9 表示匹配数字0~9
_ 表示匹配下划线
整句意思是在判断$act是否由小写字母或数字或下划线组成,如果是为true,否则为false
请问 以下 红色代码 preg_match('/[^a-z0-9_]/i', $act) 应该怎么理解呢? 麻烦会的朋友帮忙回复下,先谢啦
$act = Get('act');
if (!isset($act{0})){
$act = 'pa';
} elseif (preg_match('/[^a-z0-9_]/i', $act)){
exit;
}
谢谢 xuzuning 版主的回复
/[^a-z0-9_]/i
匹配 字母、数字、下划线 以外的字符
谢谢 fdipzone 的回复
我基本上明白这段代码的意思了。
但是我还有一个疑问:
整句意思是在判断$act是否由小写字母或 大写字母或数字或下划线组成,如果是为true,否则为false
因为 正则表达式后面是 /i
是应该这样吗?
preg_match('/[^a-z0-9_]/i', $act
preg_match 是php正则匹配方法
'/[^a-z0-9_]/i' 是匹配的正则表达式
$act 是用于检查匹配的字符串
正则表达式说明
a-z 表示匹配所有小写字母
0-9 表示匹配数字0~9
_ 表示匹配下划线
整句意思是在判断$act是否由小写字母或数字或下划线组成,如果是为true,否则为false
谢谢 fdipzone 版主的回复
我基本上明白这段代码的意思了。
但是我还有一个疑问:
整句意思是在判断$act是否由小写字母或 大写字母或数字或下划线组成,如果是为true,否则为false
因为 正则表达式后面是 /i
是应该这样吗?
if (preg_match('/[^a-z0-9_]/i', $act)) {
exit;
}
如果 $act 含有字母、数字、下划线 以外的字符,则退出
preg_match('/[^a-z0-9_]/i', $act
preg_match 是php正则匹配方法
'/[^a-z0-9_]/i' 是匹配的正则表达式
$act 是用于检查匹配的字符串
正则表达式说明
a-z 表示匹配所有小写字母
0-9 表示匹配数字0~9
_ 表示匹配下划线
整句意思是在判断$act是否由小写字母或数字或下划线组成,如果是为true,否则为false
谢谢 fdipzone 版主的回复
我基本上明白这段代码的意思了。
但是我还有一个疑问:
整句意思是在判断$act是否由小写字母或 大写字母或数字或下划线组成,如果是为true,否则为false
因为 正则表达式后面是 /i
是应该这样吗?
是的。
楼主可以查找学习简单的正则。

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