c语言中Declaration syntax error问题，紧急！

感觉你的程序问题好多~~~我改了好多处,都忘记是改哪了,呵呵~~~
你自己看下吧~~~
#include<stdio.h>
#include<stdlib.h>
#define NULL 0
typedef struct stackNode
{
char data;
struct stackNode *next;
}StackNode;
typedef struct
{
StackNode *top;
}LinkStack;

void main()
{
LinkStack *S;
StackNode *L,*p,*t;
char x,y,*a,*b;
S=(LinkStack *)malloc(sizeof(LinkStack));
a=(char *)malloc(100*sizeof(char));
b=a;
S->top=NULL;
// p=(StackNode *)malloc(sizeof(StackNode));
// L=p;
scanf("%c",&x);
while(x!='\n')
{
getchar();
p=(StackNode *)malloc(sizeof(StackNode));
p->next=S->top;
p->data=x;
// p->next=S->top;
S->top=p;
scanf("%c",&x);
}
t=S->top;

while(t)
{
printf("%c",t->data);
t=t-&g