c++ - How to check a String for special characters?

Question

I'm working on a problem in C++ and here's my question: I get a string from an object and I want to detect if there is a character that is not alphanumeric or a special character like /, (, $ and so on. I cannot imagine of a way other than asking

if (Text.Pos("A") > 0)

if (Text.Pos("B") > 0)

.....

Is there a standard way/method to do this quicker?