Printing a unicode box in C - c

Question

I'm trying to print this medium shade unicode box in C: ▒
(I'm doing the exercises in K&R and then got sidetracked on the one about making a histogram...). I know my unix term (Mac OSX) can display the box because I saved a text file with the box, and used cat textfilewithblock and it printed the block.
So far I initially tried:
#include <stdio.h>
#include <wchar.h>
int main(){
wprintf(L"▒\n");
return 0;
}
and nothing printed
iMac-2$ ./a.out
iMac-2:clang vik$
I did a search and found this: unicode hello world for C?
And it seems like I still have to set a locale (even though the executing environment in utf8? I'm still trying to figure out why this step is necessary) But anyway, it works! (after a bit of a struggle finally realizing that the proper string was en_US.UTF-8 rather than en_US.utf8 which I had read somewhere...)
#include <stdio.h>
#include <wchar.h>
#include <locale.h>
int main(){
setlocale (LC_ALL, "en_US.UTF-8");
wprintf(L"▒\n");
return 0;
}
Output is as follows:
iMac-2$ ./a.out
▒
iMac-2$
But when I try the following code...putting in the UTF-8 hex (which I got from here: http://www.utf8-chartable.de/unicode-utf8-table.pl?start=9472&unicodeinhtml=dec ) which is 0xe29692 for the box rather than pasting the box in itself, it doesn't work again.
#include <stdio.h>
#include <wchar.h>
#include <locale.h>
int main(){
setlocale (LC_ALL, "en_US.UTF-8");
wchar_t box = 0xe29692;
wprintf(L"%lc\n", box);
return 0;
}
I'm clearly missing something but can't quite figure out what it is.

Answer 1

The unicode value of the MEDIUM SHADE code point is not 0xe29692, it is 0x2592. <E2><96><92> is the 3 byte encoding for this code point in UTF-8.
You can print this thing either using the wide char APIs:
#include <stdio.h>
#include <wchar.h>
#include <locale.h>
int main(void) {
setlocale(LC_ALL, "en_US.UTF-8");
wchar_t box = 0x2592;
wprintf(L"%lc\n", box); // or simply printf("%lc\n", box);
return 0;
}
Or simply by printing the UTF-8 encoding directly:
#include <stdio.h>
int main(void) {
printf("\xE2\x96\x92\n");
return 0;
}
Or if your text editor encodes the source file in UTF-8:
#include <stdio.h>
int main(void) {
printf("▒\n");
return 0;
}
But be aware that this will not work: putchar('▒');
Also for full unicode support and a few more goodies, I recommend using iTerm2 on MacOS.

Answer 2

The box character is U+2592, which translates to 0xE2 0x96 0x92 in UTF-8. This adaptation of your third program mostly works for me:
#include <stdio.h>
#include <wchar.h>
#include <locale.h>
int main(void)
{
setlocale (LC_ALL, "en_US.UTF-8");
wchar_t box = 0xe29692;
wprintf(L"%lc\n", box);
wprintf(L"\n\nX\n\n");
box = L'\u2592'; //0xE2 0x96 0x92 = U+2592
wprintf(L"%lc\n", box);
wprintf(L"\n\n0x%.8X\n\n", box);
box = 0x2592;
wprintf(L"%lc\n", box);
return 0;
}
The output I get is:
X
▒
0x00002592
▒
The first print operation produces nothing of use; the others work.
Testing on Mac OS X 10.10.5. I happen to be compiling with GCC 5.3.0 (which I compiled), but I got the same output with XCode 7.0.2 and clang.