Recognize the max. dayes in a month

src/main.c

@@ -82,15 +82,35 @@ static int search(GtkWidget *widget, gpointer data)
 static int correct_time (GtkWidget *widget, gpointer data){
   const char *entry_day_string;
   const char *entry_month_string;
+  const char *entry_year_string;
+
+  int max_days = 30;
 
   entry_day_string = gtk_entry_get_text(entry_day);
-
   entry_month_string = gtk_combo_box_get_active_id(entry_month);
+  entry_year_string = gtk_entry_get_text(entry_year);
+
+  switch (atoi(entry_month_string))
+    {
+    case 1: case 3: case 5: case 7: case 8: case 10: case 12:
+      max_days = 31;
+      break;
+
+    case 2:
+      if ((atoi(entry_year_string)%4==0 && atoi(entry_year_string)%100!=0) || atoi(entry_year_string)%400==0) {
+        max_days = 29;
+      }
+      else{
+        max_days = 28;
+      }
+      break;
+    }
 
 
 
   g_print("Day entry: %s\n", entry_day_string);
-  g_print("Month entry: %s\n", entry_month_string);
+  g_print("Month entry: %i\n", atoi(entry_month_string));
+  g_print("Max days: %i\n", max_days);
   return 1;
 }
 
@@ -173,6 +193,7 @@ int main( int   argc, char *argv[] )
   g_signal_connect (button_now, "clicked", G_CALLBACK(set_time_now), NULL);
   g_signal_connect (button_calculate, "clicked", G_CALLBACK (calculate), NULL);
   g_signal_connect (entry_month, "changed", G_CALLBACK (correct_time), NULL);
+  g_signal_connect (entry_year, "changed", G_CALLBACK (correct_time), NULL);
 
   gtk_widget_show  (window);