C++ C++；救命啊。Can'；t返回运行总数

我必须用构造函数和析构函数制作一个计算器，每次都要加、减、乘、除，然后返回总数。出于某种原因，当我调用行“Calculator.add（num）；”或任何“Calculator.”部分时，返回一个错误，表示它“需要一个标识符”。我错过了一些简单的东西吗

谢谢。 这是我的main.cpp文件

#include <iostream>
#include "Calculator.h"
#include <cstdlib>

using namespace std;
double total;
int main(){
  while (true){
    cout << "*** Calculator *** " << endl;
    cout << "A: Add a value " << endl;
    cout << "S: Subtract a value " << endl;
    cout << "M: Multiply by a value " << endl;
    cout << "D: Divide by a value " << endl;
    cout << "T: Get the total " << endl;
    cout << "Q: Quit " << endl;
    cout << endl;
    char input;
    cin >> input;
    if (input == 'A'){
        cout << "Current Total: " << total << endl;
        cout << "Selection: A";
        cout << endl;
        cout << "*** Add selected *** " << endl;
        cout << "Value:";
        double num;
        cin >> num;
        cout << endl;
        double turnTotal = total;
        Calculator.add(num);
        cout << turnTotal << "+" << num << " = " << total;
    }
    if (input == 'S'){
        cout << "Current Total: " << total << endl;
        cout << "Selection: S";
        cout << endl;
        cout << "*** Subtract selected *** " << endl;
        cout << "Value: ";
        double num2;
        cin >> num2;
        cout << endl;
        double turnTotal2 = total;
        Calculator.subtract(num2);
        cout << turnTotal2 << "-" << num2 << "=" << total;
    }
    if (input == 'M'){
        cout << "Current Total: " << total << endl;
        cout << "Selection: M";
        cout << endl;
        cout << "*** Multiply selected *** " << endl;
        cout << "Value: ";
        double num3;
        cin >> num3;
        cout << endl;
        double turnTotal3 = total;
        Calculator.multiply(num3);
        cout << turnTotal3 << "*" << num3 << "=" << total;
    }

    if (input == 'D'){
        cout << "Current Total: " << total << endl;
        cout << "Selection: D";
        cout << endl;
        cout << "*** Divide selected *** " << endl;
        cout << "Value: ";
        double num4;
        cin >> num4;
        cout << endl;
        double turnTotal4 = total;
        Calculator.divide(num4);
        cout << turnTotal4 << "/" << num4 << "=" << total;
    }
    if (input == 'T'){
        cout << "Current Total: " << total << endl;
        cout << "Selection: T";
        cout << endl;
        cout << "*** Total selected *** " << endl;
        cout << "Value: ";
        double num5;
        cin >> num5;
        cout << endl;
        double turnTotal5 = total;
        Calculator.getTotal(num5);
        cout << turnTotal5 << "-" << num5 << "=" << total;
    }
    if (input == 'Q'){
        cout << "Thank you for using the calculator! Bye bye! Have a great day!" << endl;

    }
  }
}

#包括
#包括“Calculator.h”
#包括
使用名称空间std；
双倍总数；
int main（）{
while（true）{
cout您似乎没有首先初始化计算器。例如，您可以在主函数的开头添加初始化，如下所示

double total;
Calculator calc;
int main(){
  while (true){

然后像这样使用它

calc.add(num);

您似乎没有首先初始化计算器。例如，您可以在main函数的开头添加初始化，如下所示

double total;
Calculator calc;
int main(){
  while (true){

然后像这样使用它

calc.add(num);

Calculator
是一个类定义，您需要实例化它的一个实例才能使用它。也许您应该先了解类-
double-total=x；
这不会满足您的需要！提示：total是构造函数的局部变量。
Calculator
是一个类定义，您需要实例化一个实例也许它应该能使用它。也许你应该先学习类->代码>双总计= x；< /Cord>这不符合你的要求！提示：Tobe是构造函数的局部变量。谢谢@ JONAANTEPOTER你的编辑，我的C++技能在做了这么多JavaScript之后有点生锈了：谢谢你JONANTANKETER的编辑，它看到了我的C++技能在做了这么多JavaScript之后有点生锈了……