#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?
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2 Answers
__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.
4 Comments
user198729
Is
L in L"Virtual Cam" a native syntax of C++ or defined in some header files?
Stephane Rolland
I think it's native C++ code, since one can write wchar_t* pwstr = L"Test";
Stephane Rolland
the C++ ISO Standard referes to wchar_t as C native ;-). So L is not C++ native code, but C native code ;-)
Michael Burr
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.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.
2 Comments
user198729
But I don't see that logic above,how does it happen?
Christopher Creutzig
Where “use Unicode” means “use UTF-16 encoded Unicode,” since that is the Unicode encoding best supported by Microsoft tools and APIs.