# includeint main() { char operator; double firstNumber,secondNumber; printf("输入操作符 (+, -, *,/): "); scanf("%c", &operator); printf("输入两个数字: "); scanf("%lf %lf",&firstNumber, &secondNumber); switch(operator) { case '+': printf("%.1lf + %.1lf = %.1lf",firstNumber, secondNumber, firstNumber + secondNumber); break; case '-': printf("%.1lf - %.1lf = %.1lf",firstNumber, secondNumber, firstNumber - secondNumber); break; case '*': printf("%.1lf * %.1lf = %.1lf",firstNumber, secondNumber, firstNumber * secondNumber); break; case '/': printf("%.1lf / %.1lf = %.1lf",firstNumber, secondNumber, firstNumber / secondNumber); break; // operator doesn't match any case constant (+, -, *, /) default: printf("Error! operator is not correct"); } return 0; }