yaoqin.cpp

用两个栈实现表达式的运算

#include<iostream>
using namespace std;
#define STACKSIZE 40
#define NEWSIZE  10
#define  OK 1
#define ERROR 0
#define TURE 1
#define FALSE 0
#define OVERFLOW 0
typedef float ElemType1;
typedef char  ElemType2;
typedef int status;
typedef struct stack1{
        ElemType1 * top;
        ElemType1 * base;
        int stacksize;
        }* STACK1; //此栈存放数据 
typedef struct stack2{
        ElemType2 * top;
        ElemType2 * base;
        int stacksize;
        }* STACK2; //此栈存放操作符 

int instack(char ch);
int iostack(char ch);
status initstack(STACK1 &S1,STACK2 &S2)
{
       S2->base=(ElemType2 *)malloc(STACKSIZE * sizeof(ElemType2));
       if(!S2->base)        
       {
                          cout<<"存储分配失败。\n";
                          return OVERFLOW;
                          } 
       else
       {
             S2->top=S2->base;
             S2->stacksize=STACKSIZE;
             *S2->top++='#';
             }
       S1->base=(ElemType1 *)malloc(STACKSIZE * sizeof(ElemType1));
       if(!S1->base)        
       {
                          cout<<"存储分配失败。\n";
                          return OVERFLOW;
                          } 
       else
       {
             S1->top=S1->base;
             S1->stacksize=STACKSIZE;
             return OK;
             }
       }            
status pushstack1(STACK1 &S1,float a)
{
       *S1->top++=a;
       return OK;
       }
status pushstack2(STACK2 &S2,char ch)
{
       *S2->top++=ch;
       return OK;
       }
float popstack1(STACK1 &S1)
{
       float b;
       b=*--S1->top;
       return b;
       }
char popstack2(STACK2 &S2)
{
     char c;
     c=*--S2->top;
     return c;
     }
char gettop(STACK2 &S2)
{
     char c;
     c=*(S2->top-1);
     return c;
     }
int judge(char ch)
{
    int i;
    char str;
    str=ch;
    switch(ch)
    {
              case '+': 
              case '-': i=2;break;
              case '*': 
              case '/': i=4;break;
              case '(': i=6;break;
              case ')': i=1;break;
              case '#': i=0;break;      
    }
    return i;
}     
float summit(char ch,float a,float b)
{
	float i;
	char c=ch;                
    switch(c)
	 {
          case '+': 
                    i=a+b;break;
          case '-': 
                    i=b-a;break;
          case '*': 
                    i=a*b;break;
          case '/': 
                    i=b/a;break;
	}
	return i;
}
float inputexpress(STACK1 &S1,STACK2 &S2)
{
       int k=0;
       float a,b,sum=0,data1,data2,result;
       char c,ch,c_h,chh,p[25];
       cout<<"请输入表达式，以#结尾！\n";
       gets(p);
       //cin.getline(p,25);
       c=p[k];
       while(c!='\0')
       {
                     if(isdigit(c))
                     {
                                   a=c; 
                                   sum=sum*10+a;
                                   c=p[++k];
                                   if(!isdigit(c))
                                   {
                                                  pushstack1(S1,sum);
                                                  sum=0; 
                                                  }      
                     
                                   }
                     else
                     {
                         chh=gettop(S2);
                         while(chh!='#'||c!='#')
                         {
                                                if(judge(c)>judge(chh))
                                                {
                                                                pushstack2(S2,c);
                                                                break;
                                                                }
                                                if(judge(c)<judge(chh))
                                                {
                                                    if(c==')')
													{
																	while(chh!='(')
																	{
																		ch=popstack2(S2);
																		data1=popstack1(S1);
																		data2=popstack1(S1);
																		result=summit(ch,data1,data2);
																		pushstack1(S1,result);
																		chh=gettop(S2);
																		}
																		c_h=popstack2(S2);
                                                                    }
				                                    else                
                                                    {
                                                    
                                                                    ch=popstack2(S2);
                                                                    data1=popstack1(S1);
                                                                    data2=popstack1(S1);
                                                                    result=summit(ch,data1,data2);
                                                                    pushstack1(S1,result);
                                                                    chh=gettop(S2);
                                                                    }
                                                if(judge(c)==judge(chh))
                                                                    break;                                                        
                                                }
                         }
                     }
       c=p[++k];
       }//推出while循环 
       result=popstack1(S1);
       return result;
}
void expressresult(float consequence)
{
      float data;
      data=consequence;
      cout<<"\n\n"<<"此表达式的结果为："
          <<data<<endl;
      }

status main()
{
    float consequence;
    STACK1 S1;
    STACK2 S2;
    initstack(S1,S2);
    consequence=inputexpress(S1,S2);
    expressresult(consequence);
    return OK;
    }