printing out a unicode character with printf

Question

I am trying to print out a Ș by passing in its corresponding decimal value into printf. The output is nothing at all. Why doesn't my code work?

#include <stdio.h>
int main()
{
    printf("%lc",536);
    return 0;
}

Answer 1

On macOS Sierra 10.12.2 with GCC 6.3.0, if I run this program (compiled from mb37.c into mb37):

#include <locale.h>
#include <stdio.h>
#include <wchar.h>      /* wint_t */

int main(void)
{
    setlocale(LC_ALL, "");
    printf("%lc\n", (wint_t)536);
    return 0;
}

the output is:

$ ./mb37
Ș
$

That, I believe, is the desired output. If the setlocale() line is removed, then no output at all is produced — not even a newline. The locale used is en_US.UTF-8; my terminal handles UTF-8 too. The locale name is found by capturing and printing the return value from setlocale() — a regular string.

The wint_t cast is semi-optional; it so happens that a 64-bit compilation without the cast or the <wchar.h> header also produces the same output, but there is a mild coincidence that wint_t is the same as int. That takes some tracking; wint_t is defined as __darwin_wint_t which is defined as __darwin_ct_rune_t which is defined as int. To be portably correct, the cast is necessary. On some systems, it may not be necessary (and macOS Sierra is one such system).

The newline in the printf() is not 100% necessary, but if it is omitted, the next prompt immediately follows the U+0218 LATIN CAPITAL LETTER S WITH COMMA BELOW. It is better to ensure that the output ends with a newline.