模拟简单计算器

程序模拟简单运算器的工作：输入一个算式（没有空格），遇到‘=’号说明输入结束，输出结果。假设计算器只能进行加、减、乘、除运算，运算数和结果都是整数，4种运算符的优先级相同，按从左到右的顺序计算。例如，输入“1+2*10-10/2"后结果为10。
C++版本一

#include <stdio.h>
    #include <stdlib.h>
    
    int chartonum(char c);
    int main(int argc, char *argv[]) {
    	char str[1000];//存储算试 
    	while(gets(str)!=NULL){
    		int i;
    		int result=0;//存储结果 
    		int temp=0;//临时数据存储 
    		int flag=0;//标记是否完成第一个算术运算 
    		char c;//记录运算符 
    		for(i=0;str[i]!='\0';i++)
    		{
    			if('0'<=str[i]&&str[i]<='9'){
    				//获取两个运算符之间数 
    			temp=temp*10+chartonum(str[i]);	
    			
    			}else{
    				if(flag==1){
    					//运算 
    					switch (c){
    						case '+':
	    						result+=temp;
	    						temp=0;
	    						c=str[i];
	    						break;
    						
    						case '-':
	    						result-=temp;
	    						temp=0;
	    						c=str[i];
	    						break;
    						
    						case '*':
	    						result*=temp;
	    						temp=0;
	    						c=str[i];
	    						break;
    						
    						case '/':
	    						result/=temp;
	    						temp=0;
	    						c=str[i];
	    						break;
    					}
    											
    				}
    				else{
    					//第一个运算符处理 
    					result=temp;
    					temp=0;
    					c=str[i];
    					flag=1;
    					
    				}
    			}		
    		}	
    		printf("%d\n",result);
    		}
    	return 0;
    }
    //字符转换数字的函数 
    int chartonum(char c){
    	switch (c) {
    		case '0':return 0;
    		case '1':return 1;
    		case '2':return 2;
    		case '3':return 3;
    		case '4':return 4;
    		case '5':return 5;
    		case '6':return 6;
    		case '7':return 7;
    		case '8':return 8;
    		case '9':return 9;
    }	
    }

C++版本二
PS:与题目无关
main.cpp

/* *@Author: STZG *@Language: C++ */
#include<iostream>
#include "mymath.h"
using namespace std;
int main()
{
    long long a, b, result;
    char c;
    while(1){
        cout<<"请输入第一个数:"<<endl;
        cin>>a;
        cout<<"请输入第二个数:"<<endl;
        cin>>b;
        cout<<"请输入想要进行运算的符号:"<<endl;
        cin>>c;
        if(c=='+'){
            result=add(a,b);
        }else if(c=='-'){
            result=minu(a,b);
        }else if(c=='*'){
            result=times(a,b);
        }else if(c=='/'){
            result=divide(a,b);
        }else if(c=='%'){
            result=mod(a,b);
        }else{
            cout<<"无效运算符"<<endl;
            continue;
        }
        cout<<a<<" "<<c<<" "<<b<<" = "<<result<<endl;
    }
    return 0;
}

mymath.cpp

#include "mymath.h"
extern int add(int a,int b){
    return a+b;
}
extern long add(long a,long b){
    return a+b;
}
extern long long add(long long a,long long b){
    return a+b;
}
extern double add(double a,double b){
    return a+b;
}
extern float add(float a,float b){
    return a+b;
}
extern short add(short a,short b){
    return a+b;
}
extern int times(int a,int b){
    return a*b;
}
extern long times(long a,long b){
    return a*b;
}
extern long long times(long long a,long long b){
    return a*b;
}
extern double times(double a,double b){
    return a*b;
}
extern float times(float a,float b){
    return a*b;
}
extern short times(short a,short b){
    return a*b;
}
extern int minu(int a,int b){
    return a-b;
}
extern long minu(long a,long b){
    return a-b;
}
extern long long minu(long long a,long long b){
    return a-b;
}
extern double minu(double a,double b){
    return a-b;
}
extern float minu(float a,float b){
    return a-b;
}
extern short minu(short a,short b){
    return a-b;
}
extern int divide(int a,int b){
    return a/b;
}
extern long divide(long a,long b){
    return a/b;
}
extern long long divide(long long a,long long b){
    return a/b;
}
extern double divide(double a,double b){
    return a/b;
}
extern float divide(float a,float b){
    return a/b;
}
extern short divide(short a,short b){
    return a/b;
}
extern int mod(int a,int b){
    return a%b;
}
extern long mod(long a,long b){
    return a%b;
}
extern long long mod(long long a,long long b){
    return a%b;
}
extern short mod(short a,short b){
    return a%b;
}

mymath.h

#ifndef MYMATH_H_INCLUDED
#define MYMATH_H_INCLUDED
int add(int a,int b);
long add(long a,long b);
long long add(long long a,long long b);
double add(double a,double b);
float add(float a,float b);
short add(short a,short b);
int times(int a,int b);
long times(long a,long b);
long long times(long long a,long long b);
double times(double a,double b);
float times(float a,float b);
short times(short a,short b);
int minu(int a,int b);
long minu(long a,long b);
long long minu(long long a,long long b);
double minu(double a,double b);
float minu(float a,float b);
short minu(short a,short b);
int divide(int a,int b);
long divide(long a,long b);
long long divide(long long a,long long b);
double divide(double a,double b);
float divide(float a,float b);
short divide(short a,short b);
int mod(int a,int b);
long mod(long a,long b);
long long mod(long long a,long long b);
short mod(short a,short b);

#endif // MYMATH_H_INCLUDED

C++版本三
类与对象版本
main.cpp

/* *@Author: STZG *@Language: C++ */
#include<iostream>
#include"Calculator.h"
using namespace std;
int main()
{
    Calculator mycalculator;
    mycalculator.run();
    return 0;
}

mymath.cpp

#include "mymath.h"

extern int add(int a,int b){
    return a+b;
}
extern long add(long a,long b){
    return a+b;
}
extern long long add(long long a,long long b){
    return a+b;
}
extern double add(double a,double b){
    return a+b;
}
extern float add(float a,float b){
    return a+b;
}
extern short add(short a,short b){
    return a+b;
}
extern int times(int a,int b){
    return a*b;
}
extern long times(long a,long b){
    return a*b;
}
extern long long times(long long a,long long b){
    return a*b;
}
extern double times(double a,double b){
    return a*b;
}
extern float times(float a,float b){
    return a*b;
}
extern short times(short a,short b){
    return a*b;
}
extern int minu(int a,int b){
    return a-b;
}
extern long minu(long a,long b){
    return a-b;
}
extern long long minu(long long a,long long b){
    return a-b;
}
extern double minu(double a,double b){
    return a-b;
}
extern float minu(float a,float b){
    return a-b;
}
extern short minu(short a,short b){
    return a-b;
}
extern int divide(int a,int b){
    if(b==0){
        cout<<"除数不能为0！"<<endl;
        return -1;
    }
    return a/b;
}
extern long divide(long a,long b){
    if(b==0){
        cout<<"除数不能为0！"<<endl;
        return -1;
    }
    return a/b;
}
extern long long divide(long long a,long long b){
    if(b==0){
        cout<<"除数不能为0！"<<endl;
        return -1;
    }
    return a/b;
}
extern double divide(double a,double b){
    if(b==0){
        cout<<"除数不能为0！"<<endl;
        return -1;
    }
    return a/b;
}
extern float divide(float a,float b){
    if(b==0){
        cout<<"除数不能为0！"<<endl;
        return -1;
    }
    return a/b;
}
extern short divide(short a,short b){
    if(b==0){
        cout<<"除数不能为0！"<<endl;
        return -1;
    }
    return a/b;
}
extern int mod(int a,int b){
    if(b==0){
        cout<<"模数不能为0！"<<endl;
        return -1;
    }
    return a%b;
}
extern long mod(long a,long b){
    if(b==0){
        cout<<"模数不能为0！"<<endl;
        return -1;
    }
    return a%b;
}
extern long long mod(long long a,long long b){
    if(b==0){
        cout<<"模数不能为0！"<<endl;
        return -1;
    }
    return a%b;
}
extern short mod(short a,short b){
    if(b==0){
        cout<<"模数不能为0！"<<endl;
        return -1;
    }
    return a%b;
}

mymath.h

#ifndef MYMATH_H_INCLUDED
#define MYMATH_H_INCLUDED
#include<iostream>
using namespace std;
int add(int a,int b);
long add(long a,long b);
long long add(long long a,long long b);
double add(double a,double b);
float add(float a,float b);
short add(short a,short b);
int times(int a,int b);
long times(long a,long b);
long long times(long long a,long long b);
double times(double a,double b);
float times(float a,float b);
short times(short a,short b);
int minu(int a,int b);
long minu(long a,long b);
long long minu(long long a,long long b);
double minu(double a,double b);
float minu(float a,float b);
short minu(short a,short b);
int divide(int a,int b);
long divide(long a,long b);
long long divide(long long a,long long b);
double divide(double a,double b);
float divide(float a,float b);
short divide(short a,short b);
int mod(int a,int b);
long mod(long a,long b);
long long mod(long long a,long long b);
short mod(short a,short b);

#endif // MYMATH_H_INCLUDED

Calculator.cpp

#include "Calculator.h"

Calculator::Calculator()
{
    a=0;
    b=0;
    result=0;
    //ctor
}

Calculator::~Calculator()
{
    //dtor
}
void Calculator::run(){
    while(1){
        cout<<"请输入第一个数:"<<endl;
        cin>>a;
        cout<<"请输入第二个数:"<<endl;
        cin>>b;
        cout<<"请输入想要进行运算的符号:"<<endl;
        cin>>c;
        if(c=='+'){
            result=add(a,b);
        }else if(c=='-'){
            result=minu(a,b);
        }else if(c=='*'){
            result=times(a,b);
        }else if(c=='/'){
            result=divide(a,b);
        }else if(c=='%'){
            result=mod(a,b);
        }else{
            cout<<"无效运算符"<<endl;
            continue;
        }
        cout<<a<<" "<<c<<" "<<b<<" = "<<result<<endl;
    }
}

Calculator.h

#ifndef CALCULATOR_H
#define CALCULATOR_H
#include<iostream>
#include "mymath.h"
using namespace std;
class Calculator
{
    public:
        Calculator();
        virtual ~Calculator();
        void run();
    protected:

    private:
    long long a, b, result;
    char c;
};

#endif // CALCULATOR_H