Question

enum state{
    state_Mmenu,            // State 0
    state_settingmenu,      // State 1
    state_gamemenu,         // State 2
    state_savegamemenu,     // State 3
    state_loadgamemenu,     // State 4;
    state_Exit,             // State 5;
    state_other
};

state stateMmenu();
state statesettingmenu(string, string);
state stategamemenu();
state statesavegamemenu(string, string, string, ofstream&);
state stateloadgamemenu(string, string, string, ifstream&);
state stateExit();



int main()
{
    state curr=state_other;

    string filename= "PlayerOne.jak";
    string fname="Player";
    string lname="One";
    ifstream inFS;
    ofstream outFS;

    while(curr != state_Exit)
    {
        switch(curr)
        {
            case state_Mmenu:
                curr = stateMmenu();
                break;

            case state_settingmenu:
                curr = statesettingmenu(fname, lname);
                break;

            case state_gamemenu:
                curr = stategamemenu();
                break;

            case state_savegamemenu:
                curr = statesavegamemenu(fname, lname, filename, outFS);
                break;

            case state_loadgamemenu:
                curr = stateloadgamemenu(fname, lname, filename, inFS);
                break;

            default:
                cout << "Don't Tip the Vending Machine"<<endl;
                curr = state_Mmenu;
                break;
        }
    }

    return 0;
}


state statesavegamemenu(string fname, string lname, string filename,
                        ofstream outFS)
{
    state next=state_savegamemenu;
    int choice4=0;
    cout<<" -Save Game Menu-----------------"<<endl;
    cout<<"1. File Name - "<<filename<<endl;
    cout<<"2. Save" <<endl;
    cout<<"3. Game Menu" <<endl;
    cout<<"----------------------------"<<endl;
    do
    {
        cout << "Choice? "<< endl;
        cin >> choice4;
        cin.clear();
        cin.ignore(10000,'\n');

    } while(!cin.good());

    switch(choice4)
    {
        case 1:
        {
            cout<<"What would you like to save this file as? ";
            cin>>filename;
            cout<<endl;
            next = state_savegamemenu;
        }
            break;
        case 2:
        {
            outFS.open(filename.c_str());
            if(!outFS.is_open())
            {
                next = state_savegamemenu;
                break;
            }
            else
            {
                outFS<<fname<<endl;
                outFS<<lname<<endl;
            }
            outFS.close();
            next = state_savegamemenu;
        }

            break;
        case 3:
            next = state_gamemenu;
            break;
        default:
            cout << "Bad Input!"<<endl;
            next = state_savegamemenu;
            break;
    }
    cout <<endl;
    return next;
}

state stateloadgamemenu(string fname, string lname, string filename,
                        ifstream inFS)
{
    state next=state_loadgamemenu;
    int choice5=0;
    cout<<" -Save Game Menu-----------------"<<endl;
    cout<<"1. File Name - "<<filename<<endl;
    cout<<"2. Load" <<endl;
    cout<<"3. Main Menu" <<endl;
    cout<<"----------------------------"<<endl;
    string filecontent;
    do
    {
        cout << "Choice? "<< endl;
        cin >> choice5;
        cin.clear();
        cin.ignore(10000,'\n');

    } while(!cin.good());

    switch(choice5)
    {
        case 1:
        {
            cout<<"What file would you like to load? ";
            cin>>filename;
            cout<<endl;
            next = state_loadgamemenu;
        }
            break;
        case 2:
        {
            inFS.open(filename.c_str());
            if(!inFS.is_open())
            {
                next = state_savegamemenu;
                break;
            }
            else
            {
                while(!inFS.eof())
                {
                    inFS >> filecontent;
                    if(inFS.good())
                    {
                        cout << filecontent << endl; 
                    }
                }
            }
            inFS.close();
            next = state_loadgamemenu;
        }

            break;
        case 3:
            next = state_Mmenu;
            break;
        default:
            cout << "Bad Input!"<<endl;
            next = state_loadgamemenu;
            break;  
    }
    cout <<endl;
    return next;
}

所以我的问题是在代码中我试图用来自用户的cin覆盖文件名。问题是，当我刷新状态机时，文件名不会被覆盖，它仍然是我在int main（）中命名的“playerone.jak”。如果有人知道为什么会这样，那将非常感激。

Answer 1

此功能

matched: 3 active includes:
 - iostream
 - fstream
 - boost/spirit/home/x3.hpp

应该是

state stateloadgamemenu(string fname, string lname, string filename,
                        ifstream inFS)

原因是当您在C ++中传递字符串或任何对象时，它会通过值传递，这意味着被调用函数内的任何更改都不会保存到原始变量中。

通过引用传递它意味着同一个对象将从被调用函数返回给调用者。

您可以查看此问题以获取更多详细信息 Pass by Reference / Value in C++

使用cin时不会覆盖字符串变量

1 个答案: