C++ Access violation reading location 0xFFFFFFFFFFFFFFFF when using func identifier

Question

I am using Visual Studio 2017 and I set the project to use ISO C++14 Standard under C/C++->Languages

The debugger cannot recognize __func__ predefined identifier and it crashes if I try to use it as a string with error:

: Access violation reading location 0xFFFFFFFFFFFFFFFF

What am I missing to be able to use this identifier?

Code sample if needed

printf("%S\n", __func__);

Thanks

Can you attach a small, compilabe example with which the error occurs? — foolo, Dec 17 '19 at 21:11
*and it crashes if I try to use it as a string with error:* -- Please post a [mcve]. — PaulMcKenzie, Dec 17 '19 at 21:11
Why are you using `%S` as the format string? This seems to be a case of using `printf` incorrectly, not that `__func__` cannot be used. And if this is C++, why not take the extra step of trying `cout` instead of `printf` to see if that is an issue? — PaulMcKenzie, Dec 17 '19 at 21:16
Take precisely example from https://learn.microsoft.com/en-us/cpp/preprocessor/predefined-macros?view=vs-2017 and try it out do not change %s to %S — Öö Tiib, Dec 17 '19 at 21:17
Also, doesn't Visual C++ 17 warn you of the format string not matching the argument? — PaulMcKenzie, Dec 17 '19 at 21:19

score 3 · Accepted Answer · answered Dec 17 '19 at 21:17

3

static const char __func__[];

printf() with a capital S as a conversion specifier is an extension that requires a wchar_t*.

Solution, use a lowercase s:

printf("%s\n", __func__);

or

std::cout << __func__ << '\n';

answered Dec 17 '19 at 21:17

Ted Lyngmo

C++ Access violation reading location 0xFFFFFFFFFFFFFFFF when using __func__ identifier