Undefined reference when using ncurses on linux

Question

I'm trying to start developing a program using ncurses on Linux. I can't even get the Hello World example to compile. Here's the code:

#include <curses.h>

int main()
{         
        initscr();
        printw("Hello, world.");
        refresh();
        getch();
        endwin();
        return 0;
}

When I attempt to compile, I get:

hello.c:(.text+0x12): undefined reference to `initscr'

For every one of those called functions.

I installed ncurses via apt-get, and also by downloading the sources and compiling, installing, etc.

I have tried #include both curses.h and ncurses.h.

What is going on?

Answer 1

I was having a similar issue and found a solution which helped me, but was slightly different from the other answers posted here. I was trying to use the panels library with curses and my compile command was:

$ gcc -o hello hello.c -lncurses -lpanel

when I read the other answers, I was baffled because I was including the -lncurses flag, but it still was not compiling, and with similar errors to what you were getting:

$ gcc -o hello hello.c -lncurses -lpanel
/usr/lib/gcc/i686-linux-gnu/4.7/../../../../lib/libpanel.a(p_new.o): In function `new_panel':
p_new.c:(.text+0x18): undefined reference to `_nc_panelhook'

I finally found my answer in the tldp:

"To use panels library functions, you have to include panel.h and to link the program with panels library the flag -lpanel should be added along with -lncurses in that order."

So, it appears that order is important when using the compile flags! I tried switching the order:

gcc -o hello hello.c -lpanel -lncurses

This allowed it to compile successfully. I know you already have your answer, so I hope this helps someone.

Answer 2

As Greg Hewgill said, you need to pass in -lcurses or -lncurses to link to the curses library.

gcc -o hello hello.c -lncurses

You also probably mean to use initscr() and getch(). Once I make those substitutions, the above compiles for me.