#define _CRT_SECURE_NO_WARNINGS #include<stdio.h> int main() { //四舍五入用double类型 double Num1 = 0, Num2 = 0; char operation = '0'; //使用double类型需要使用%lf scanf("%lf%c%lf", &Num1, &operation, &Num2); if (operation == '+') printf("%.4lf%c%.4lf=%.4lf\n", Num1, operation,...