问题
How can I copy a volatile std::string? There is no copy constructor for volatile, nor does something like c_str allow volatile access. operator= also doesn't seem to allow setting a volatile. It seems like std::string is simply unusable as a volatile object. Is this intended, or am I missing some way to use it?
NOTE: I have easy workarounds, I just came upon the issue while trying to use string in some low-level code.
回答1:
As you noted, none of the member functions on std::string are marked volatile, so you can't perform any operations on a volatile std::string. I think the only option would be to cast away volatileness and perform operations on the result, as shown here:
const_cast<std::string&>(myVolatileString) = "Now I'm different!"
Fundamentally, though, you probably shouldn't be making a volatile std::string. volatile is appropriate for objects that might be mutated by external sources or changed by multiple threads. This first case is pretty unusual and would require some very special hardware that knew the layout of std::string. The second is unsafe because std::string isn't thread-safe.
Hope this helps!
来源：https://stackoverflow.com/questions/19623434/how-to-copy-set-a-volatile-stdstring