Question

I have the following statement:

vsnprintf(target, size - 1, "%ls_%ls", str16_1, str16_2);

Why does this fail on gcc?

I used this on Windows like this:

vsnprintf(target, size - 1, "%S_%S", str16_1, str16_2);

and it’s working as expected. On gcc documentation I found that %S is synonym with %ls, but I must not use it. I tried also with %S, but is not working. I use this in a function with variable argument list. Is it possible to not work because I change the format variable that I pass to va_start? I must search %S and replace it with %ls in format variable.

The function is something like:

void f(const char* format, ...){
  char* new_format = format with %S replaced with %ls;
  va_list argptr;
  va_start(args, format);
  vsnprintf(str, size-1, new_format, argptr);
}

I checked and new_format is correct.

Thank you!

Answer 1

Because I use this on Mac I found a work-around:

How to "pass on" a variable number of arguments to NSString's +stringWithFormat:

It seems that vsnprintf can’t handle 16 bits string. Maybe because wchar_t isn’t 16 bits.