happytoday wrote:
> I failed to compile that program as written below with those error
> messages :
> The conditions of compiling this program are not available any longer
> in the net so please help me compiling this program .
>
> Error messages :
> ------------------------
> root @ Homer /export/home/unix.d/programs.d/clang.d/GUI>cc plot_data.c
> "plot_data.c", line 15: warning: implicit function declaration:
> create_int_dialog_entry
> "plot_data.c", line 16: warning: implicit function declaration:
> create_float_dialog_entry
> "plot_data.c", line 20: warning: implicit function declaration:
> set_up_dialog
> "plot_data.c", line 24: warning: implicit function declaration:
> read_dialog_window

Your REALLY should declare your functions! This will tell the compiler
what sort of things should be passed to the functions as arguments and
the type of the the value returned by the function.

K&R C, which allowed you to omit such things, is hopelessly obsolete.

> Undefined first referenced
> symbol in file
> create_int_dialog_entry plot_data.o
> create_float_dialog_entry plot_data.o
> read_dialog_window plot_data.o
> set_up_dialog plot_data.o
> ld: fatal: Symbol referencing errors. No output written to a.out
>
>
> Sources code :
> ------------------------
> #include </usr/openwin/share/include/X11/Xlib.h>
> #include </usr/openwin/share/include/X11/Xutil.h>
> #include <stdio.h>
> #include <math.h>
>
> int main()
> {
> /* Define default values: */
>
> int n = 0;
> float x = 0.0;
>
> /* Define contents of dialog window */
>
> create_int_dialog_entry("n", &n);

It's conventional, though not required, for a function like the above to
return "success" or "failure". Good programmers test the return code
and write diagnostic messages when a function returns a failure code.

> create_float_dialog_entry("x", &x);
Test the return code!
>
> /* Create window with name "Setup" and top-left corner at (0,0) */
>
> set_up_dialog("Setup", 0, 0);
Test the return code!
>
> /* Display the window and read the results */
>
> read_dialog_window();
>
> /* Print out the new values */
>
> printf("n = %d, x = %f\n", n, x);
> return 0;
> }

Dirty little hacks like this have a nasty habit of turning up as part of
something important and embarrassing the authors!

If it's worth doing, it's worth doing it well!!