LinkedList를 활용한 Stack구현

Linked List를 활용한 Stack구현이다.

#include <stdio.h>
#include <stdlib.h>
 
typedef struct StackNode{
 
    int data;
    struct StackNode *link;
 
}StackNode;
typedef struct {
    
    struct StackNode *top;
 
}StackType;
void init(StackType *s)
{
    s->top=NULL;
}
int is_empty(StackType *s)
{
    return (s->top == NULL);
}
void stack_push(StackType *s , int data)
{
    StackNode *in_stack = (StackNode*)malloc(sizeof(StackNode));
 
    if(in_stack == NULL)
    {
        printf("할당에러\n");
        return;
    }
    else
    {
        in_stack->data = data;
        in_stack->link = s->top;
        s->top = in_stack;
    }
}
int stack_pop(StackType * s)
{
    int data;
    if(is_empty(s))
    {
        printf("스택이 비어있음\n");
        return -1;
    }
    else
    {
        StackNode * tmp = s->top;
        data = tmp->data;
        s->top = tmp->link;
        free(tmp);
        return data;
    }
}
int main()
{
    StackType s;
    init(&s);
    stack_push(&s,1);
    stack_push(&s,2);
    stack_push(&s,3);
 
    printf("%d\n",stack_pop(&s));
    printf("%d\n",stack_pop(&s));
    printf("%d\n",stack_pop(&s));
    printf("%d\n",stack_pop(&s));
 
    return 0;
}