I have a problem when using printf
and wprintf
functions together in code. If the regular string is printed first, then wprintf
doesn't work. If I use wprintf
first then printf
doesn't work.
#include <stdio.h> #include <wchar.h> #include <stdlib.h> #include <locale.h> int main() { setlocale(LC_ALL,""); printf("No printing!\n"); wprintf(L"Printing!\n"); wprintf(L"Wide char\n"); printf("ASCII\n"); return 0; }
Outputs:
No printing! ASCII
While
#include <stdio.h> #include <wchar.h> #include <stdlib.h> #include <locale.h> int main() { setlocale(LC_ALL,""); wprintf(L"Printing!\n"); printf("No printing!\n"); wprintf(L"Wide char\n"); printf("ASCII\n"); return 0; }
outputs:
Printing! Wide char
I'm using gcc (GCC) 4.6.1 20110819 together with glibc 2.14 on 64bit Linux 3.0.
This is to be expected; your code is invoking undefined behavior. Per the C standard, each FILE
stream has associated with it an "orientation" (either "byte" or "wide) which is set by the first operation performed on it, and which can be inspected with the fwide
function. Calling any function whose orientation conflicts with the orientation of the stream results in undefined behavior.
To complement R..'s accepted answer:
While this is very rarely done, checking the return code of printf
/wprintf
would more clearly indicate that one of them is not working (it should return -1 for the print function which is invalid according to the current orientation of the stream).
Unfortunately, a common pattern for checking errors in standard library functions:
if (wprintf(...) == -1) { perror("wprintf"); ... }
May not help much here: if the stream is set to output non-wide characters, and you call wprintf
, errno
may not be set and you'll get wprintf: Success
, which does not provide much information.
So indeed this is a somewhat hard to understand issue when you don't know about the character orientation of streams.
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With