Trouble with _TCHAR and using _tcslen

[fullchaos13]

Hey guys, I recently started reading the book Programming Windows Fifth Edition by Charles Petzold and I came about a roadblock. The book mentions a _TCHAR type that I could use for either Unicode or ASCII support depending on whether or not _UNICODE is defined. It also mentions that _TCHAR comes with its own functions. The one I'm trying to use is _tcslen().

The problem is, every time I try using _tcslen() I get an error saying _tcslen was not declared in this scope.

#include <windows.h>
#include <string.h>
#define _UNICODE
#define UNICODE

int main(){

 _TCHAR x = 'a';
 int tester = 0;

 tester = tcslen(x);


return 0;
}

I'm currently using CodeBlocks as my IDE.

[LB]

_UNICODE and UNICODE must be defined before including any Windows header. You would normally define these in your project settings, not in any source or header file.

[fullchaos13]

Thanks for the quick reply LB! So I just defined both in my project settings (I'm using CodeBlocks) It was under Project > Build Options > Define. I still get the same Error. The compiler doesn't seem to understand what _tcslen() is, even though I was able to find reference for it on countless MSDB pages. I find this strange because the compiler has no problem with _TCHAR.

[LB]

I didn't realize you said you were using CodeBlocks - you're probably using GCC or MinGW which doesn't have full proper Windows support. If you want to do Windows development you should just install Visual Studio 2015 - it's free and will save you many headaches.

[helios]

If you're just going to #define UNICODE (which is probably for the best) then there's no point in using _tcslen(). Just use wcslen().

[JLBorges]

#include <tchar.h> (It is part of MinGW.)

// comment out the next two lines to switch to narrow characters
#define _UNICODE
#define UNICODE

#include <windows.h>
#include <string.h>
#include <tchar.h> 

int main() {

    TCHAR tstr[] = TEXT( "abcdef" ) ; // note TEXT()

    const unsigned int len = _tcslen(tstr) ;
    const unsigned int sz = sizeof(tstr) / sizeof( tstr[0] ) ; // note: divide by sizeof(TCHAR)

    _tprintf( TEXT( "tstr == %s  length: %u  size: %u\n" ), tstr, len, sz );

    TCHAR c = TEXT('!') ;
    tstr[2] = c ;
    _tprintf( TEXT( "tstr == %s  tstr[2] == %c\n"), tstr, tstr[2] ) ;
}

[fullchaos13]

@JLBorges Thanks a lot mate! Including <tchar.h> made the program run. Also thanks for writing out that piece of code, it definitely helped me understand how TCHAR and _tcslen works much better.