如何在不同的switch case语句上使用对象的类成员函数？

Question

我的课程-：用于创建，显示对角矩阵

class Diagonal {
private:
    int *A;
    int n;
public:
    Diagonal(){
        n=2;
        A = new int[n];
    }
    Diagonal(int n){
        this->n = n;
        A = new  int[n];
    }
    void Create(){
        cout<<"Enter the Elements : "
        for(int i =0; i<=n; i++){
            cin>>A[i-1];
        }
    }
    void Set(int i, int j,  int x){
        if(i==j){
            A[i-1] = x;
        }
    }
    int Get(int i, int j){
    if(i == j){
        return A[i-1];
        }
    else{
        return 0;
        }
    }
    void display(){
        for(int i=1; i<n; i++){
            for(int j=1; j<n; j++){
                if(i==j){
                    cout<<A[i-1]<<" ";
                }
                else{
                    cout<<"0 ";
                }
            }
            cout<<endl;
        }
    }
~Diagonal(){
delete []A;
}
};
void functionName(){
cout<<"----- Functions ------"<<endl;
cout<<"1. Create "<<endl;
cout<<"2. Get "<<endl;
cout<<"3. Set "<<endl;
cout<<"4. Display "<<endl;
cout<<"5. Exit "<<endl;}

具有嵌套do-while循环和切换大小写的主要功能：

int main(){
int ch,fun;
 do{
        cout<<"------ Menu --------"<<endl;
        cout<<"1. Diagonal "<<endl;
        cout<<"2. Lower Tri-angular "<<endl;
        cout<<"3. Upper Tri-angular "<<endl;
        cout<<"4. Tri-diagonal"<<endl;
        cout<<"5. Toplitz"<<endl;
        cout<<"6. Exit"<<endl;

        cout<<endl;

        cin>>ch;

        do{
            int n;
        switch(ch)
        {
            case 1: functionName();
            cin>>fun;
                switch(fun){

                     case 1:
                       {
                        cout<<"Enter the size of matrix : " ;
                        cin>>n;
                        Diagonal d(n);
                        d.Create();
                       }
                        break;
                    case 2:
                        //how to call d.get();
                        break;
                    case 3:
                        //how to call d.set();
                        break;
                    case 4:
                        //how to call d.display();
                        break;
                    case 5:
                        break;
            }
            break;
            case 2: functionName();

            break;
            case 3: functionName();

            break;
            case 4: functionName();

            break;
            case 5: functionName();

            break;
        }

    }while(fun<4);

  }while(ch<=5);
 return 0;
 }

我的问题是如何在案例1中创建的相同obj的不同切换案例中调用类成员函数？

1. 如何调用d.get（）;如果是2
2. 如何调用d.set（）;如果是3

当我调用这些成员函数时发生错误，“在此范围内未声明d”有什么方法可以在switch语句中调用这些成员函数？

Answer 1

您可以使用唯一的指针：

int main(){
int ch,fun;
 do{
        cout<<"------ Menu --------"<<endl;
        cout<<"1. Diagonal "<<endl;
        cout<<"2. Lower Tri-angular "<<endl;
        cout<<"3. Upper Tri-angular "<<endl;
        cout<<"4. Tri-diagonal"<<endl;
        cout<<"5. Toplitz"<<endl;
        cout<<"6. Exit"<<endl;

        cout<<endl;

        cin>>ch;

        do{
            int n;
            auto d = std::make_unique<Diagonal>();
        switch(ch)
        {
            case 1: functionName();
            cin>>fun;
                switch(fun){

                     case 1:
                       {
                        cout<<"Enter the size of matrix : " ;
                        cin>>n;
                        d = std::make_unique<Diagonal>(n);
                        d->Create();
                       }
                        break;
                    case 2:
                        //how to call d.get();
                        d->get();
                        break;
                    case 3:
                        //how to call d.set();
                        d->set();
                        break;
                    case 4:
                        //how to call d.display();
                        d->display();
                        break;
                    case 5:
                        break;
            }
            break;
            case 2: functionName();

            break;
            case 3: functionName();

            break;
            case 4: functionName();

            break;
            case 5: functionName();

            break;
        }

    }while(fun<4);

  }while(ch<=5);
 return 0;
 }