What header do I need in order to use UNIX library punction clear()

all I was compiling a source of my UNIX today when I noticed the following

warning: implicit declaration of function 'clear'

After I made a debug with the GDB on the binary, these came out:

0x090000002a242594 in clear () from /usr/lib/libcurses.a(shr42_64.o)
0x090000002a242600 in wclear () from /usr/lib/libcurses.a(shr42_64.o)
0x090000002a238a80 in werase () from /usr/lib/libcurses.a(shr42_64.o)
0x090000002a238b00 in wmove () from /usr/lib/libcurses.a(shr42_64.o)
0x090000002a238a9c in werase () from /usr/lib/libcurses.a(shr42_64.o)
0x090000002a238600 in wclrtobot () from /usr/lib/libcurses.a(shr42_64.o)
0x090000002a237f80 in wclrtoeol () from /usr/lib/libcurses.a(shr42_64.o)

It seems that it's some kind of a UNIX library "libcurses.a"

How should I include this library in my file in order to get rid of that warning ?

#include <stdlib.h>
#include <curses.h> // See it's here, stop the silly questions
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <time.h>

Thanks !

Solution

From the stacktrace showing shr42_64.o, your system seems to be some version of AIX, e.g., 5.x for example. Running

ar tv /usr/lib/libcurses.a

would show something like

r--r--r--     2/2     493219 Aug 05 05:38 2011 shr42.o
r--r--r--     2/2     377211 Aug 05 05:38 2011 shr4.o
r--r--r--     2/2     194484 Aug 05 05:38 2011 shr.o

The corresponding header /usr/include/curses.h has the prototype for clear() ifdef'd within

#if     defined(NOMACROS) || defined(lint)

#if defined(__STDC__) || !defined(_NO_PROTO)

and (assuming your compiler really uses that header) the latter line is what is used. From the comment about gdb, it seems likely that you also are using gcc. Usually gcc will define __STDC__ (though some very old port may not). If there is no problem with that definition, it is possible that something defined _NO_PROTO. Alternatively, your system could have some conflicting header file. To resolve what is the case, I would generate the preprocessor-output file (using options -E, -P and -C as documented) and look to see which "curses.h" file was included, and which ifdef was actually used.