glib 자료구조 중에 gptrarray 에 대해 질문 있습니다 !!

  1 #include <stdio.h>
  2 #include <glib.h>
  3 
  4 typedef struct _DATA {
  5         int item;
  6         char* name;
  7         int price;
  8         double value;
  9 } DATA;
 10 
 11 int compare_items (gpointer, gpointer);
 12 void printAll (gpointer, gpointer);
 13 
 14 DATA* data [] = {{7143, "A", 1231234, 235.5},
 15                 {5231, "B", 532458, 238.75},
 16                 {8751, "C", 872654, 125.47}};
 17 
 18 int main(void)
 19 {
 20     GPtrArray* a = g_ptr_array_new ();
 21     g_ptr_array_add (a, data[0]);
 22     g_ptr_array_add (a, data[1]);
 23     g_ptr_array_add (a, data[2]);
 24 
 25     /* g_ptr_array_sort (a, (GCompareFunc) compare_items); */ 
 
 26     DATA* temp = (DATA*) g_ptr_array_index (a, 1); 
 27     int k = temp -> item; 
 28     /* printf ("item : %d\n", temp -> item); */ 
 29  
 30     /* g_ptr_array_foreach (a, printAll, (gpointer) NULL); */ 
 31  
 32     return 0; 
 33 } 
 34  
 35 int compare_items (gpointer a, gpointer b) { 
 36         DATA* alpha = (DATA *) a; 
 37         DATA* beta = (DATA *) b; 
 38  
 39         return alpha->item - beta->item; 
 40 } 
 41  
 42 void printAll (gpointer a, gpointer b) { 
 43         DATA* alpha = (DATA*) a; 
 44         printf ("item : %d, name : %s, price : %d, value : %lf\n", alpha -> item, alpha -> name, alpha -> price, alpha ->    value); 
 45         return; 
 46 }