Can't get a simple GTK3 application to work

Question

All I want is just a simple dialog to select a file for processing. I didn't use C lang for a while, and I can't find a good working example.

code:

#include <gtk/gtk.h>
#include <stdio.h>

int main(int argc, char const *argv[]) {

  GtkFileChooserNative *native;

  native = gtk_file_chooser_native_new ("Open File", NULL, GTK_FILE_CHOOSER_ACTION_OPEN, NULL, NULL);

  return 0;
}

I compile it with this command:

gcc `pkg-config gtk+-3.0 --cflags` `pkg-config gtk+-3.0 --libs` -o out dialog.c

I am having segmentation fault on gtk_file_chooser_native_new ()

Maybe strace will help:

http://pastebin.com/TdC0A2J3

Answer 1

You need to call gtk_init (before any other GTK function), or have your own application class and call g_application_run. And your main should be int main(int argc, char**argv) as usual.

The following program does not segfault (on Linux/Debian/Sid, GTK is 3.22.7)

#include <gtk/gtk.h>
#include <stdio.h>
int main (int argc, char  **argv) {
  GtkFileChooserNative *native = NULL;
  gtk_init (&argc, &argv);
  native = gtk_file_chooser_native_new ("Open File", NULL,
             GTK_FILE_CHOOSER_ACTION_OPEN, NULL, NULL);
  guint res = gtk_native_dialog_run (GTK_NATIVE_DIALOG (native));
  if (res == GTK_RESPONSE_ACCEPT) {
    char *filename;
    GtkFileChooser *chooser = GTK_FILE_CHOOSER (native);
    filename = gtk_file_chooser_get_filename (chooser);
    printf ("should open %s\n", filename);
    g_free (filename);
  }
  /// in a real application perhaps you want: gtk_main ();
  return 0;

}

and does show a dialog. Compile that using

 gcc -Wall -g $(pkg-config gtk+-3.0 --cflags) \
    $(pkg-config gtk+-3.0 --libs) \
    -o out dialog.c

and use the gdb debugger when debugging.