c++练习—实现简单的4则运算

Posted 2022-04-16 mountaincold

#pragma once
class Counter

public:
    void setExp(const char* exp);//设置表达式
    void cleanExp(); //清除表达式
    void countExp();//计算表达式
    int reExp();//返回结果

private:
    char m_exp[20];
    int m_Num1;
    int m_Num2;
    int sum;
    void sub(int n);//整理表达式，分离两个两个运算数
;

counter类 counter.h     

counter.cpp

#include "Counter.h"
#include <string.h>
#include <stdlib.h>
void Counter::setExp(const char* exp)

    strcpy_s(m_exp, 20, exp);

void Counter::sub(int n)

    char num1[20];
    char num2[20];
    int len=strlen(m_exp);
    for (int i=0;i<len;i++)
    
        if (i<n)
        
            num1[i] = m_exp[i];
        
        if (i>n)
        
            num2[i - n-1] = m_exp[i];
        
    
    m_Num1 = atoi(num1);
    m_Num2 = atoi(num2);

void Counter::cleanExp()

    strcpy_s(m_exp, 20, 0);

void Counter::countExp()

    for (int i=0;i<20;i++)
    
        switch (m_exp[i])
        
        case ‘+‘: 
        
            sub(i);
            sum = m_Num1 + m_Num2;
        break;
        case ‘-‘: 
            sub(i);
            sum = m_Num1 - m_Num2;
         break;
        case ‘*‘: 
            sub(i);
            sum = m_Num1 * m_Num2;
         break;
        case ‘/‘: 
            sub(i);
            sum = m_Num1 / m_Num2;
         break;
        default:
            break;
        
    

int Counter::reExp()

    return sum;

测试test.cpp

#include <iostream>
#include <stdio.h>
#include "Counter.h"
int main()

Counter count;
char str[20];
printf("请输入所需要计算的表达式：");
scanf_s("%s",str,20);
count.setExp(str);
count.countExp();
std::cout << "结果为："<<count.reExp() << std::endl;