我不想在字符串中允许多种模式,例如,
$string = "php in stackoverflow"; // multiple spaces not allowed
$string = "php in--stackoverflow"; // multiple hyphens not allowed
$string = "php in__stackoverflow"; // multiple underscores not allowed
etc
所以,它适用于这些行,
if(preg_match('/\s\s+/', $string)) echo "only a single spaces are allowed";
if(preg_match('/\-\-+/', $string)) echo "only a single hyphens are allowed";
if(preg_match('/\_\_+/', $string)) echo "only a single underscores are allowed";
我也不想让下面的组合模式和上面的行不起作用,
$string = "php in -stackoverflow"; // a space with a hyphen not allowed
$string = "php in-_stackoverflow"; // a hyphens with a underscore not allowed
$string = "php in_ stackoverflow"; // a underscore with a space not allowed
etc
知道我可以用一个简单的脚本来实现这一点吗?
这就是字符类的用途,匹配多个字符。
if(preg_match('/[\s-_][\s-_]+/', $string)) echo "only a single space, hyphen or underscore is allowed";
preg_match('/--+|^-+|-+$/', $string)
这在 else if 中失败。但单独来看它是有效的。有什么想法吗??