This code places five Elementary clock widgets on a window, each of them exemplifying a part of the widget's API.

The first of them is the pristine clock:

   /* pristine (no seconds, military time) */
   ck = elm_clock_add(win);
   elm_box_pack_end(bx, ck);
   evas_object_show(ck);

As you see, the defaults for a clock are:

military time
no seconds shown

For am/pm time, see the second clock:

   /* am/pm */
   ck = elm_clock_add(win);
   elm_clock_show_am_pm_set(ck, EINA_TRUE);
   elm_box_pack_end(bx, ck);
   evas_object_show(ck);

The third one will show the seconds digits, which will flip in synchrony with system time. Note, besides, that the time itself is different from the system's -- it was customly set with elm_clock_time_set():

   /* with seconds and custom time */
   ck = elm_clock_add(win);
   elm_clock_show_seconds_set(ck, EINA_TRUE);
   elm_clock_time_set(ck, 10, 11, 12);
   elm_box_pack_end(bx, ck);
   evas_object_show(ck);

In both fourth and fifth ones, we turn on the edition mode. See how you can change each of the sheets on it, and be sure to try holding the mouse pressed over one of the sheet arrows. The forth one also starts with a custom time set:

   /* in edition mode, with seconds, custom time and am/pm set */
   ck = elm_clock_add(win);
   elm_clock_edit_set(ck, EINA_TRUE);
   elm_clock_show_seconds_set(ck, EINA_TRUE);
   elm_clock_show_am_pm_set(ck, EINA_TRUE);
   elm_clock_time_set(ck, 10, 11, 12);
   elm_box_pack_end(bx, ck);
   evas_object_show(ck);

The fifth, besides editable, has only the time units editable, for hours, minutes and seconds. This exemplifies elm_clock_edit_mode_set():

   /* in edition mode, with seconds, but only some digits editable */
   ck = elm_clock_add(win);
   elm_clock_show_seconds_set(ck, EINA_TRUE);
   elm_clock_edit_set(ck, EINA_TRUE);
   digedit = ELM_CLOCK_EDIT_HOUR_UNIT | ELM_CLOCK_EDIT_MIN_UNIT | ELM_CLOCK_EDIT_SEC_UNIT;
   elm_clock_edit_mode_set(ck, digedit);
   elm_box_pack_end(bx, ck);
   evas_object_show(ck);

See the full source code for this example.