求一个算数表达式的值，输入后先转化成后缀表达式输出，然后输出运算结果，我是用VC6.0编译的，有错误和警告，麻烦大家给改改，谢谢！

#include <stdio.h>
#include <conio.h>
#include <malloc.h>

typedef struct node                  /*栈节点定义*/
{   char data;
    struct node *next;
 }snode,*slink;

int Emptystack(slink S)              /*检测栈空*/
{  if(S==NULL) return(1);
    else return(0);   
 }

char Pop(slink *top)               /*出栈*/
{   char e;
    slink p;
    if(Emptystack(*top)) return(-1);
    else
    {   e=(*top)->data;
        p=*top;*top=(*top)->next;
        free(p);return(e);
     }
 }

void Push(slink *top,char e)      /*进栈*/
{  slink p;
   p=(slink)malloc(sizeof(snode));
   p->data=e;
   p->next=*top;
   *top=p;
 }

void Clearstack(slink *top)          /*置空栈*/
{  slink p;
   while(*top!=NULL)
   { p=(*top)->next;
     Pop(top);
     *top=p;
    }
  *top=NULL;
 }



char Getstop(slink S)                 /*取栈顶*/
{ if（S!=NULL）return(S->data);
   return(0);
 }

int Precede(char x,char y)             /*比较x是否“大于”y*/
{ switch(x)
{    case '(':x=0;break;
     case '+':
     case '-':x=1;break;
     case '*':
     case '/':x=2;break;
   }
  switch(y)
  {  case '+':
     case '-':y=1;break;
     case '*':
     case '/':y=2;break;
     case '(':y=3;break;
   }
  if(x>=y)return(1);
   else return(0);
 }





void mid_post(char B[],char E[])   /*中缀表达式到后缀表达式的转换*/
{   int i=0,j=0;
    char x;
    slink S=NULL;
    Push(&S,'#');
    do
    {   x=E[i++];
        switch(x);
        { case '#':
          {   while(!Emptystack(S))
              B[j++]=Pop(&S);
           }break;
        case ')':
          {   while(Getstop(S)!='(')
              B[j++]=Pop(&S);
              Pop(&S);
           }break;
          case '+':
          case '-':
          case '*':
          case '/':
          case '(':
          {   while(Precede(Getstop(S),x))
               B[j++]=Pop(&S);
              Push(&S,x);
           }break;
          default:B[j++]=x;
          }
      }while(x!='#');
 }

int postcount(char B[])   /*后缀表达式求值*/
{  int i=0;
   char x;
   float z,a,b;
   slink S=NULL;
   while(B[i]!='#')
   { x=B[i];
     switch(x)
     { case '+':b=Pop(&S);a=Pop(&S);z=a+b;Push(&S,z);break;
       case '-':b=Pop(&S);a=Pop(&S);z=a-b;Push(&S,z);break;
       case '*':b=Pop(&S);a=Pop(&S);z=a*b;Push(&S,z);break;  
       case '/':b=Pop(&S);a=Pop(&S);z=a/b;Push(&S,z);break;
       default:x=B[i]-'0';Push(&S,x);
      }
      i++;
    }
    if(!Emptystack(S)) return(Getstop(S));
}

void main()
{  char B[255],E[255]=" ";
   printf("请输入要处理的中缀表达式：\n");
   scanf("%s",E);
   printf("相应的后缀表达式为：\n");
   mid_post(B,E);
   printf("%s\n",B);
   printf("表达式的值为：%d",postcount(B));
   getch();
}