Printing a Unicode Symbol in C

Question

I'm trying to print a unicode star character (0x2605) in a linux terminal using C. I've followed the syntax suggested by other answers on the site, but I'm not getting an output:

#include <stdio.h>
#include <wchar.h>
int main(){
    wchar_t star = 0x2605;
    wprintf(L"%c\n", star);
    return 0;
}

I'd appreciate any suggestions, especially how I can make this work with the ncurses library.

Solution 1

Two problems: first of all, a wchar_t must be printed with %lc format, not %c. The second one is that unless you call setlocale the character set is not set properly, and you probably get ? instead of your star. The following code seems to work though:

#include <stdio.h>
#include <wchar.h>
#include <locale.h>
int main() {
    setlocale(LC_CTYPE, "");
    wchar_t star = 0x2605;
    wprintf(L"%lc\n", star);
}

And for ncurses, just initialize the locale before the call to initscr.

Solution 2

Whether you are using stdio or ncurses, you have to initialize the locale, as noted in the ncurses manual. Otherwise, multibyte encodings such as UTF-8 do not work.

wprintw doesn't necessarily know about wchar_t (though it may use the same underlying printf, this depends on the platform and configuration).

With ncurses, you would display a wchar_t in any of these ways:

• storing it in an array of wchar_t, and using waddwstr, or
• storing it in a cchar_t structure (with setcchar), and using wadd_wch with that as a parameter, or
• converting the wchar_t to a multibyte string, and using waddstr

Comments

[Luke Collins]

@chux Well, I can print a with value 0x0061 but not ǎ with value 0x01ce.

[Luke Collins]

This fixed it, thanks! ★ Any ideas how to mvwprint this with ncurses though?

[Luke Collins]

Thanks for the reply. I keep getting an implicit declaration error for the wide-character ncurses functions, are there some other libraries I need to be including?

[Antti Haapala -- Слава Україні]

stackoverflow.com/questions/15222466/…

[Thomas Dickey]

You're missing a #define. Generally that should be _XOPEN_SOURCE_EXTENDED, but most platforms have fubar'd ifdef's: for Linux just use -D_GNU_SOURCE. You'll have to link with -lncursesw`, but that's not implicit declaration

[Luke Collins]

can you explain a bit more?

[Thomas Dickey]

It would be defined using ncursesw5-config --cflags, or via a ".pc" file, depending on how ncurses is packaged for your system.