CODEWITHSUNDEEP
clinuxncursesarchlinux
Blingu
Blingu

Reputation: 51

ncursesw functions not declared

I need to use ncurses with unicode support, so I included the following line to my .c file.

#include <curses.h>

In my makefile I'm using -lncursesw as a flag. When calling functions like get_wch(), it tells me "implicit declaration of function". I'm on Arch Linux so I installed ncurses with pacman -S ncurses. In /usr/include I can find cursesw.h, but it doesn't have functions like get_wch() declared. Under /lib I can find libcursesw.so, so what's the matter?

Upvotes: 3

Views: 1554

Answers (2)

Thomas Dickey
Thomas Dickey

Reputation: 54485

Use <curses.h>, read the header file to see which definition you prefer using:

/* 
 * With XPG4, you must define _XOPEN_SOURCE_EXTENDED, it is redundant (or 
 * conflicting) when _XOPEN_SOURCE is 500 or greater.  If NCURSES_WIDECHAR is   
 * not already defined, e.g., if the platform relies upon nonstandard feature   
 * test macros, define it at this point if the standard feature test macros 
 * indicate that it should be defined. 
 */
#ifndef NCURSES_WIDECHAR
#if defined(_XOPEN_SOURCE_EXTENDED) || (defined(_XOPEN_SOURCE) && (_XOPEN_SOURCE - 0 >= 500))
#define NCURSES_WIDECHAR 1
#else  
#define NCURSES_WIDECHAR 0
#endif
#endif /* NCURSES_WIDECHAR */

(just NCURSES_WIDECHAR should be enough). This is summarized in the manual page.

If you read cursesw.h, you might notice that it is for the C++ binding.

As suggested in another answer, you can get some help from the pkg-config program. However, that gives different results for Arch Linux:

$ pkg-config ncurses --cflags --libs
-D_DEFAULT_SOURCE -D_XOPEN_SOURCE=600 -Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now -lncursesw 
$ pkg-config ncursesw --cflags --libs
-D_DEFAULT_SOURCE -D_XOPEN_SOURCE=600 -Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now -lncursesw

That is, the Arch Linux packager has equated the two configurations of ncurses; both selections in pkg-config use the ncursesw library. The Arch Linux package does have a libncurses.so, but that is only a text-file telling the linker to use libncursesw.so. Because of the way it is packaged, on Arch Linux it makes no difference which library you use.

(offhand, combining _GNU_SOURCE and _DEFAULT_SOURCE is incorrect, probably not from any distribution's packaging system, because the former was deprecated in ncurses five years ago).

Upvotes: 1

MestreLion
MestreLion

Reputation: 13676

-lncursesw is a linker flag, and by itself is not enough to enable wide char support. You should also add the compiler flag -I/usr/include/ncursesw. Without this your #include <curses.h> will end up including /usr/include/curses.h instead of /usr/include/ncursesw/curses.h

If you want a more standard way to find out required linker and compiler flags, you can use pkg-config. See the difference between those:

$ pkg-config ncurses --cflags --libs
-D_GNU_SOURCE -D_DEFAULT_SOURCE -lncurses -ltinfo

$ pkg-config ncursesw --cflags --libs
-D_GNU_SOURCE -D_DEFAULT_SOURCE -I/usr/include/ncursesw -lncursesw -ltinfo

Upvotes: 2

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