#define NAME(x) TEXT(x)
#define TEXT(quote) __TEXT(quote) // r_winnt
#define __TEXT(quote) quote // r_winnt
The above is from winNT.h, isn't NAME("Virtual Cam") the same as "Virtual Cam",what's the point to use this macro?
views:
74answers:
2
+1
A:
Depends on if your system is #defined to use Unicode. Then it will automatically change the literal for you to be a wide literal instead of a char literal.
DeadMG
2010-08-18 12:12:49
But I don't see that logic above,how does it happen?
2010-08-18 12:15:04
@user198729: see the `#ifdef UNICODE` `#else` part of the code in the header file.
Naveen
2010-08-18 12:16:54
Where “use Unicode” means “use UTF-16 encoded Unicode,” since that is the Unicode encoding best supported by Microsoft tools and APIs.
Christopher Creutzig
2010-08-18 13:26:19
+2
A:
__TEXT macro expansion is selected based on whether UNICODE flag is defined or not. If not it just expands to quote else it will append L to the quote so that it becomes L"Virtual Cam" . This string is interpreted as a wide char string.
Naveen
2010-08-18 12:14:55
Is `L` in `L"Virtual Cam"` a native syntax of C++ or defined in some header files?
2010-08-18 12:39:31
I think it's native C++ code, since one can write wchar_t* pwstr = L"Test";
Stephane Rolland
2010-08-18 12:53:10
the C++ ISO Standard referes to wchar_t as C native ;-). So L is not C++ native code, but C native code ;-)
Stephane Rolland
2010-08-18 12:57:08
The '`L`' prefix to a string or character literal is in *both* the C and C++ language standards - it's how wide-character literals are formed in the source.
Michael Burr
2010-08-18 16:07:45