数制转换（c语言）

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

#define true 1
#define false 0

typedef  struct Node
{
int data;
struct Node *pNext;
}NODE, *PNODE;

typedef struct Stack
{
PNODE pTop;
PNODE pBottom;
}STACK, *PSTACK;

void init(PSTACK pS);
void push(PSTACK pS, int val);
int pop(PSTACK pS);
int empty(PSTACK pS);

int main ()
{
STACK s;
int val;
int e;
int i;
init(&s);
printf("please input a data: ");
scanf("%d",&val);
while (val)
{
push(&s,val % 8);
val /= 8;
}
while (!empty(&s))
{
e = pop(&s);
printf("%d",e);
}

return 0;
}

void init(PSTACK pS)
{
pS->pTop = (PNODE)malloc(sizeof(NODE));
if (NULL == pS->pTop)
{
printf("malloc error!\n");
exit(-1);
}
else
{
pS->pBottom = pS->pTop;
pS->pTop->pNext = NULL;
}
}

void push(PSTACK pS, int val)
{
PNODE pNew = (PNODE)malloc(sizeof(NODE));
pNew->data = val;
pNew->pNext = pS->pTop;
pS->pTop = pNew;
}

int empty(PSTACK pS)
{
if (pS->pTop == pS->pBottom)
{
return true;
}
else
return false;
}

int pop(PSTACK pS)
{
int e;
if (empty(pS))
return false;
else
{
PNODE r = pS->pTop;
e = r->data;
pS->pTop = r->pNext;
free(r);
r = NULL;
}
return e;
}