printf, wprintf, %s, %S, %ls, char* and wchar*: Errors not announced by a compiler warning?

I suspect GCC (mingw) has custom code to disable the checks for the wide printf functions on Windows. This is because Microsoft's own implementation (MSVCRT) is badly wrong and has %s and %ls backwards for the wide printf functions; since GCC can't be sure whether you will be linking with MS's broken implementation or some corrected one, the least-obtrusive thing it can do is just shut off the warning.

The format specifers matter: "%s" says that the next string is a narrow string ("ascii" and typically 8 bits per character). "%S" means wide char string. Mixing the two will give "undefined behaviour", which includes printing garbage, just one character or nothing.

One character is printed because wide chars are, for example, 16 bits wide, and the first byte is non-zero, followed by a zero byte -> end of string in narrow strings. This depends on byte-order, in a "big endian" machine, you'd get no string at all, because the first byte is zero, and the next byte contains a non-zero value.

At least in Visual C++: printf (and other ACSII functions): %s represents an ASCII string %S is a Unicode string wprintf (and other Unicode functions): %s is a Unicode string %S is an ASCII string

As far as no compiler warnings, printf uses a variable argument list, with only the first argument able to be type checked. The compiler is not designed to parse the format string and type check the parameters that match. In cases of functions like printf, that is up to the programmer