我写的简单计算器代码？请高手指点一下，不胜感谢！

#include<stdio.h>
void main()
{
    double operand1,operand2,result;
    char ch;
    printf("请输入计算式：\n");
    do
    {
        scanf("%lf%c",&operand1,&ch);
        while(ch!='=')
        {
            scanf("%lf",&operand2);
            switch(ch)
            {
            case '+':
                result=operand1+operand2;
                operand1=result;
                scanf("%c",&ch);
                break;
            case '-':
                result=operand1-operand2;
                operand1=result;
                scanf("%c",&ch);
                break;
            case '*':
                result=operand1*operand2;
                operand1=result;
                scanf("%c",&ch);
                break;
            case '/':
                if(operand2!=0)
                     {
                         result=operand1/operand2;
                           operand1=result;
                        scanf("%c",&ch);
                     }
                    else
                         ch='=';    
                 break;
            case '%':
                if(operand2!=0)
                 {
                         result=(int)operand1%(int)operand2;
                        operand1=result;
                        scanf("%c",&ch);
                 }
                    else
                         ch='=';    
                break;
            default :
                printf("你的运算符错误，请重新编译输入计算式：\n");
                
                break;

            }
        }
        if(operand2!=0)
            printf("%f\n",result);
        else
            printf("运算数为零，请重新编译输入计算式：\n");
    
    }while(operand2!=0);
    
    
}
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