C/GLib: Call a function every second

2023-10-25

The following code creates a callback that calls a function every second and prints the current time:

C
#include <glib.h>
//
// Callback for printing current time
//
gboolean
timeout_callback (gpointer data)
{
  //
  // Initialize current time
  //
  GDateTime *time;
  {
    time = g_date_time_new_now (g_time_zone_new_local ());
    if (time == NULL)
      {
	return FALSE;
      }
  }
  //
  // Print current time
  //
  {
    g_print ("Current time: %02d:%02d:%02d\n", g_date_time_get_hour (time),
	     g_date_time_get_minute (time), g_date_time_get_second (time));
  }
  return TRUE;
}
//
// main function
//
int
main ()
{
  //
  // Initialize main loop
  //
  GMainLoop *loop;
  {
    loop = g_main_loop_new (NULL, FALSE);
  }
  //
  // Add callback to perform every second
  //
  {
    g_timeout_add (1000, timeout_callback, loop);
  }
  //
  // Start main loop
  // 
  {
    g_print ("Starting main loop (CTRL+C to quit) ...\n");
    g_main_loop_run (loop);
  }
  //
  // End main loop
  //
  {
    g_main_loop_unref (loop);
  }
}

Compiling

Compile with:

Shell
cc `pkg-config --cflags glib-2.0` main.c `pkg-config --libs glib-2.0`

Excecuting

Execute program with:

Shell
./a.out

Output

Output:

Starting main loop (CTRL+C to quit) ...
Current time: 21:19:17
Current time: 21:19:18
Current time: 21:19:19
Current time: 21:19:20
Current time: 21:19:21
^C

Press CTRL+C to end program.

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