Regex to find out if the sequence has any special characters

I am looking for a regex to find out the given word sequence has any special characters.

For example.

In this input string

    "test?test";

I would like to find out the words got

    "test(any special char(s) inclu开发者_如何学Cding space)test" 

You can just use [^A-Za-z0-9], which will match anything that is not alphanumeric, but of course it depends on what you consider a "special character." If underscore is not special [\W] can be a shortcut for anything that is not a word (A-Za-z0-9_) character.

You don't really need a regex here. If you want to test for alphanumeric characters, you car use LINQ, for example (or just iterate over the letters):

string input = "test test";
bool valid = input.All(Char.IsLetterOrDigit);

Char.IsLetterOrDigit checks for all Unicode alphanumeric characters. If you only want the English ones, you can write:

public static bool IsEnglishAlphanumeric(char c)
{
    return ((c >= 'a') && (c <= 'z'))
        || ((c >= 'A') && (c <= 'Z'))
        || ((c >= '0') && (c <= '9'));
}

and use it similarly:

bool valid = input.All(IsEnglishAlphanumeric);