Escape sequence for ? in c++

开发者_如何学运维I was looking at the escape sequences for characters in strings in c++ and I noticed there is an escape sequence for a question mark. Can someone tell me why this is? It just seems a little odd and I can't figure out what ? does in a string. Thanks.

It's to keep a question mark from getting misinterpreted as part of a trigraph.

For example, in

"What??!"

The "??! would be interpreted as the | character. So, you have to escape the question marks as follows:

"What\?\?!"

Example complements of http://msdn.microsoft.com/en-us/library/bt0y4awe%28VS.80%29.aspx