Stack with Dynamic allocation, C (vc)

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//Microsoft (R) C/C++ Optimizing Compiler Version 19.00.23506 for x64

#include  <stdio.h>
#include  <stdlib.h>

#define MAX_STACK_SIZE 100
typedef int element;
typedef struct {
    element *data;
    int capacity;
    int top;
}StackType;

void init_stack(StackType *s)
{
    s->top = -1;
    s->capacity = 1;
    s->data = (element *) malloc(s->capacity * sizeof(element));   
}

int is_empty(StackType *s)
{
    return (s->top == -1);
}

int is_full(StackType *s)
{
    return(s->top == MAX_STACK_SIZE - 1 );
}

void push(StackType *s,element item)
{
    if(is_full(s))
    {
        s->capacity *= 2;
        s->data = (element *) realloc(s->data,s->capacity * sizeof(element));
    }
    s->data[++(s->top)] = item;
}
element pop(StackType *s)
{
   if(is_empty(s)) 
   {
       fprintf(stderr,"스택이 비었습니다."); 
       exit(1);
   }
   else return s->data[(s->top)--];
}

int main(void)
{
    StackType *s;
    s = (StackType *) malloc (sizeof(StackType));
    init_stack(s);
    push(s,1);
    push(s,2);
    push(s,3);
    printf("%d\n",pop(s));
    printf("%d\n",pop(s));
    printf("%d\n",pop(s));
    free(s->data);
    return 0;
}

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Compilation time: 1,21 sec, absolute running time: 0,32 sec, absolute service time: 1,56 sec