使用PHP preg_match检查多个模式和组合模式

Question

我不想在字符串中允许多个模式，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

我有什么想法可以通过一个简单的脚本来实现这个目标吗？

Answer 1

这是字符类的用途，匹配多个字符。

if(preg_match('/[\s-_][\s-_]+/', $string)) echo "only a single space, hyphen or underscore is allowed";