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

int PrintError = 0;
/*全局变量，0代表正常，1代表表达式出错*/

/*char类型链表式堆栈，用来存放运算符号，以及用在中缀表达式转换等时候*/
typedef struct Node *PtrToNode;
typedef PtrToNode Stack;
int IsEmpty(Stack S);
void MakeEmpty(Stack S);
void Push(char X,Stack S);
char Top(Stack S);
void Pop(Stack S);

typedef struct Node{
 char Element;
 PtrToNode Next;
};

/*float类型链表式堆栈，用来存放操作数*/
typedef struct FNode *Ptr_Fn;
typedef Ptr_Fn FStack;
int FisEmpty(FStack S);
void FPush(float X,FStack S);
float FTop(FStack S);
void FPop(FStack S);
 
typedef struct FNode{
 float Element;
 Ptr_Fn Next;
};

void ConvertToPost(FILE *In, Stack Whereat,FILE *Temp);
void Reverse(Stack Rev);
void Calculate(FILE *Change, Stack Whereat,FILE *Temp);

/******主函数******/
int main()
{
 FILE *InputFile, *OutputFile,*Temp;    /*初始化变量*/
 Stack Whereat; 
 char sample;
 InputFile = fopen("Input.txt","r");     /*打开文件*/
 OutputFile = fopen("Output.txt","w");

 Whereat = malloc(sizeof(struct Node));    /*给 Whereat分配空间*/
 Whereat->Next = NULL;
 if (!InputFile || !OutputFile) {                   /*错误处理*/
  printf("intput or output file(s) do not exist.\n");
  return(1);
 }
 sample = getc(InputFile);          
 while ( sample != EOF){
  Temp = fopen("Temp.txt","w+");     /*生成Temp文件*/
  ungetc(sample,InputFile);      /* put back sample字符*/
  ConvertToPost(InputFile,Whereat,Temp);   /*中缀变后缀*/
  if (PrintError){                             /*错误处理*/
   fprintf(OutputFile,"Error in infix notation."); 
   fscanf(InputFile,"\n",&sample);
   PrintError = 0;
  }
  else if (IsEmpty(Whereat) == 1){              /*跳过在input文件中的空格*/
  }
  else if (IsEmpty(Whereat) != 1){
   Reverse(Whereat);
   if (Top(Whereat) == 'B'){       /*错误处理，*/
                                           /*A表示操作数B表示运算符*/
    PrintError = 1;         /*后缀表达式第一个元素应是操作数而不是运算符号*/
   }
  fclose(Temp);
  Temp = fopen("Temp.txt","r+");     
  Calculate(OutputFile, Whereat,Temp);   /*计算结果*/
  }
  fclose(Temp);         
  MakeEmpty(Whereat);      /* 清空Whereat用来处理下一行*/
  putc('\n',OutputFile);      /* 在输出文件中换行*/
  sample = getc(InputFile);     
 }