需要两个为Glist对象的减法在C

Question

假设：

g1和g2是存在以下字符（未一个char **）一个为Glist对象

g1 = {"a", "b", "c"}; 

g2 = {"b", "d", "e"}; 

我需要用c的码返回列表减法的glist库;

g3 = subtract (g1, g2); 
should return 
{"a", "c"); 

g4 = subtract (g2, g1); 
should return 
{"d", "e"); 

Answer 1

void glist_deep_copy_g_func(gpointer data, gpointer user_data) { 
    GList** result = user_data; 
    if (data) { 
     *result = g_list_append(*result, strdup(data)); 
    } 
    user_data = result; 
} 

GList* glist_deep_copy(GList* source) { 
    GList* result = NULL; 
    g_list_foreach(source, &glist_deep_copy_g_func, &result); 
    return result; 
} 

gint glib_compare_char_ptr(gconstpointer a, gconstpointer b) { 
    return strcmp(a, b); 
} 

GList* glist_subtract(GList* from, GList* by) { 
    GList* result = NULL; 

    if (from && by) { 
     result = glist_deep_copy(from); 
     for (GList *node_from = g_list_first(from); node_from; node_from = 
       g_list_next(node_from)) { 
      for (GList *node_by = g_list_first(by); node_by; node_by = 
        g_list_next(node_by)) { 
       if (!strcmp(node_from->data, node_by->data)) { 
        GList* node = g_list_find_custom(result, node_from->data, 
          &glib_compare_char_ptr); 
        char* data = node->data; 
        result = g_list_remove(result, node->data); 
        free(data); 
       } 
      } 
     } 
    } else if (from) { 
     return glist_deep_copy(from); 
    } 

    return result; 
} 

Answer 2

您可以查看的std::set_difference实施和适应它glist。

GLib本身没有设置差异的实现。