利用逆波兰(Reverse Polish Notation, RPN)的后缀表达法计算四则运算表达式

char sInput[]="9+(3-1)*3+8/2";  //output 931-3*+82/+

#include "stdio.h"
#include "stdlib.h"
#include "math.h"
#include "time.h"

#define OK 1
#define ERROR 0
#define TRUE 1
#define FALSE 0
#define MAXSIZE 20 /* 存储空间初始分配量 */

typedef int Status; 
typedef char SElemType; /* SElemType类型根据实际情况而定，这里假设为int */

/* 顺序栈结构 */
typedef struct
{
        SElemType data[MAXSIZE];
        int top; /* 用于栈顶指针 */
}SqStack;

Status visit(SElemType c)
{
        printf("%d ",c);
        return OK;
}

/*  构造一个空栈S */
Status InitStack(SqStack *S)
{ 
        /* S.data=(SElemType *)malloc(MAXSIZE*sizeof(SElemType)); */
        S->top=-1;
        return OK;
}

/* 把S置为空栈 */
Status ClearStack(SqStack *S)
{ 
        S->top=-1;
        return OK;
}

/* 若栈S为空栈，则返回TRUE，否则返回FALSE */
Status StackEmpty(SqStack S)
{ 
        if (S.top==-1)
                return TRUE;
        else
                return FALSE;
}

/* 返回S的元素个数，即栈的长度 */
int StackLength(SqStack S)
{ 
        return S.top+1;
}

/* 若栈不空，则用e返回S的栈顶元素，并返回OK；否则返回ERROR */
Status GetTop(SqStack S,SElemType *e)
{
        if (S.top==-1)
                return ERROR;
        else
                *e=S.data[S.top];
        return OK;
}

/* 插入元素e为新的栈顶元素 */
Status Push(SqStack *S,SElemType e)
{
        if(S->top == MAXSIZE -1) /* 栈满 */
        {
                return ERROR;
        }
        S->top++;                /* 栈顶指针增加一 */
        S->data[S->top]=e;  /* 将新插入元素赋值给栈顶空间 */
        return OK;
}

/* 若栈不空，则删除S的栈顶元素，用e返回其值，并返回OK；否则返回ERROR */
Status Pop(SqStack *S,SElemType *e)
{ 
        if(S->top==-1)
                return ERROR;
        *e=S->data[S->top];    /* 将要删除的栈顶元素赋值给e */
        S->top--;                /* 栈顶指针减一 */
        return OK;
}

/* 从栈底到栈顶依次对栈中每个元素显示 */
Status StackTraverse(SqStack S)
{
        int i;
        i=0;
        while(i<=S.top)
        {
                visit(S.data[i++]);
        }
        printf("\n");
        return OK;
}
Status StackOut(SqStack S)
{
        int i;
        i=S.top;
        while(i >-1)
        {
                printf("%c\n",S.data[i--]);
        }
        printf("\n");
        return OK;
}

#include"test.h"

/* is number ? */
int isNumber (char i){
    if(i<58 && i>47){
      return 1;
    }else{
      return 0;
    }
}

/* is logic operator ? */
int isLogic (char i){
  if(i == 42 || i == 43 || i == 45 || i == 47)
  {
    return 1;
  }else{
    return 0;
  }
}

/* get logic symbol prior*/
int prior (char i){
  switch(i)
  {
    case ‘-‘:
      return 1;
    case ‘+‘:
      return 1;
    case ‘/‘:
      return 2;
    case ‘*‘:
      return 2;
  }
}

int main(){

  char sInput[]="9+(3-1)*3+8/2";  //output 931-3*+82/+int i = 0;
  SqStack myStack;
  InitStack(&myStack);

  printf("start\n");
  //todo: other way to loop char array
  while(sInput[i] != ‘\0‘){
    char cCur = sInput[i];
    if(isNumber(cCur)){
      printf("%c\n",cCur);
    }else{
      if(cCur == 41)    // 41 is ‘)‘
      {
        char cB;
        cB = ‘1‘;
        while(cB != 40)  // 40 is ‘(‘
        {
          if(cB != ‘1‘){
            printf("%c\n",cB);
          }
          Pop(&myStack,&cB);
        }
      }else{  //none num and not ‘)‘
        if(isLogic(cCur) && isLogic(myStack.data[myStack.top]))
        {
          if(prior(cCur) <= prior(myStack.data[myStack.top]))
          {
            while(myStack.top > -1)
            {
              char cE;
              Pop(&myStack,&cE);
              printf("%c\n",cE);
            }
            Push(&myStack,cCur);
          }else{
            Push(&myStack,cCur);
          }
        }else{
          //printf("%c\n",cCur);
          Push(&myStack,cCur);
        }
      }
    }
    i++;
  }
  //printf("top:%i\n", myStack.top);
  StackOut(myStack);
  printf("\nend\n");
  return 0;
}

start
9
3
1
-
3
*
+
8
2
/
+


end