Checking multiple contains on one string

How about this?

    if(input.IndexOfAny(new char[] { ',', '/', '\\', '.' })>=0)
    {

    }

Consider using Regex (specify characters you want to check in brackets - remember that some of them must be escaped):

Regex.IsMatch(input, @"[,/]");

or

new[] {",", "/"}.Any(input.Contains)

Does this win for shortest?

@".,/\".Any(input.Contains)