Trying to pass string literals as template arguments [duplicate]

Answer 1

You can't use string literals as a template argument, for the simple reason that it's unspecified whether two instances of a literal with the same text are the same object or not. In other words, given:

template 
class TC {};

TC< "xyz" > v1;
TC< "xyz" > v2;

It would be unspecified whether v1 and v2 had the same type or not.

You can use char const[] variables as template arguments, however, since they have a defined address:

template 
class TC {};

extern char const xyz[] = "xyz";
TC< xyz > v1;
TC< xyz > v2;

In this case, v1 and v2 are guaranteed to have the same type.

EDIT:

I think C++11 removes the need for the extern on the definition of the string, at least if the string and the instantiation are all in the same translation unit. I'm not sure, however; the one time I did something like this, I didn't have access to C++11.