_tcslen in Multibyte character set: how to convert WCHAR [1] to const char * ?

Question

I search over internet for about 2 hours and I don't find any work solution.

My program have multibyte character set, in code i got:

 WCHAR value[1];

 _tcslen(value);

And in compiling, I got error:

'strlen' : cannot convert parameter 1 from 'WCHAR [1]' to 'const char *'

How to convert this WCHAR[1] to const char * ?

Answer 1

use conversion function WideCharToMutliByte() .

http://msdn.microsoft.com/en-us/library/dd374130(VS.85).aspx

Answer 2

I assume the not-very-useful 1-length WCHAR array is just an example...

_tcslen isn't a function; it's a macro that expands to strlen or wcslen according to the _UNICODE define. If you're using the multibyte character set (which means _UNICODE ISN'T defined) and you have a WCHAR array, you'll have to use wcslen explicitly.

(Unless you're using TCHAR specifically, you probably want to avoid the _t functions. There's a not-very-good overview in MSDN at http://msdn.microsoft.com/en-us/library/szdfzttz(VS.80).aspx; does anybody know of anything better?)

Answer 3

_tcslen takes WCHAR pointers or arrays as input only when UNICODE is #defined in your enviroment.

From the error message, I'd say that it isn't

The best way to define unicode is to pass it as a parameter to the compiler. For Microsoft C, you would use the /D switch

cl -c /DUNICODE myfile.cpp

or you could change your array declaration to TCHAR, which like _tcslen will be char when UNICODE is not #defined and WCHAR when it is.

Answer 4

Try setting "use unicode" in your projects settings in VS if you want _tcslen to be wcslen, set it to "use multibyte" for _tcslen to be strlen. As some already pointed out, _t prefixed functions (as many others actually, e.g. MessageBox()) are macros that are "expanded" based on the _UNICODE precompiler define value.

Another option would be to use TCHAR instead of WCHAR in your code. Although I'd say a better idea would be to just stick to either wchar_t or char types and use appropriate functions with them.

And last but not least, as the question is tagged c++, consider using std::string (or std::wstring for that matter) and std::vector instead of char buffers. Using those with C API functions is trivial and generally a lot safer.