返回堆棧data-structure實現中pop函數的void**值

我的鍛煉狀態如下：

stack stack_push(stack s);
stack stack_pop(stack s, void **d);
//The second parameter of stack_pop function is requested in order to pass back to the caller the data fetched from the stack.

我在返回pop函數后移除的元素的值時遇到了問題：我無法返回移除元素的值，因為pop函數已經返回堆棧本身；因此，我應該使用void **d變量返回該值。

但當我試圖讀取STACK.C文件中的i變量時，出現了分段錯誤。（堆棧應該處理不同的數據類型，這就是為什么我使用了一個container結構，以便為數據類型存儲一個int（例如，1代表int，2代表float，etc.)，以及void* value變量中的有效值）。

STACK.H

typedef struct _stack stack;
typedef struct _node node;
typedef struct _container container;

struct _node{
   void *data;
   struct _node *below;
};

struct _stack{
   node *base;
   node *top;
};

struct _container{
   int i;
   void *value;
};
#define STACK_EMPTY {NULL,NULL}

STACK.C

int main(){
   
   stack my_stack = STACK_EMPTY;
   
   ...

      switch(chose){
         case 1:
            my_stack = stack_push(my_stack);
            break;
         case 2:
            void **d = NULL; //d will contains the returned value.
            my_stack = stack_pop(my_stack, d);     
            container *cont = (container*)*d; 
            printf("%d", cont->i); //SEGMENTATION FAULT ERROR HERE
            break;
         case 3:
            stack_print(my_stack);
            break;
         default:
            break;
      }      
   }
}

STACK_OPERATIONS.H

#define MAX_STRING_SIZE 15

stack stack_push(stack s){
   ...
   int *push_int = malloc(sizeof(int));
   float *push_float = malloc(sizeof(float));;
   char *push_char = malloc(sizeof(char));;
   char *push_char_arr = malloc(sizeof(char)*MAX_STRING_SIZE+1);

   node *my_node = malloc(sizeof(struct _node));
   container *my_container = malloc(sizeof(struct _container));

   my_node->data = my_container;

   switch(chose_push){
      case 1:
         ...
         my_container->i = 1;
         my_container->value = push_int; 
      case 2:
         ...
         my_container->i = 2;
         my_container->value = push_float;
      case 3:
         ...
         my_container->i = 3;
         my_container->value = push_char;
      case 4:
         ...
         my_container->i = 4;
         my_container->value = push_char_arr;     
   }

   if(s.base == NULL && s.top == NULL){
      //Stack is empty
      my_node->below = NULL;
      s.base = my_node;
      s.top = my_node;
   } else {
      my_node->below = s.top;
      s.top = my_node;
   }
   return s;
}

stack stack_pop(stack s, void **d){
   if(s.base == NULL && s.top == NULL){
      //Stack is empty
      puts("Stack is empty: cannot execute pop.");
   } else {
      node *my_node_1 = s.top;
      node *my_node_2 = my_node_1;
      my_node_1 = my_node_1->below;
      
      d = my_node_2->data; //Here I'm assigning back the d variable
      
      free(my_node_2);
      
      s.top = my_node_1;
      if(my_node_1==NULL) s.base = NULL;
   }
   return s;
}