C ++ if語句沒有返回

Question

int main()
{
char command = 'a';
Monster Goblin;Goblin.HP = 5;Goblin.name = "Goblin";
if(command == 'a'){
    cout<<"At the main Menu, what to do now? Enter H for a list of commands!"<< endl;
    cin>>command;
    switch(command)
    {
        case 'a':
            cout<<"Going to the main menu!"<<endl;
            command = 'a';
            break;
        case 'b':
            cout<<"Going to command line B"<<endl;
            command = 'b';
            break;
        case 'c':
            cout<<"going to command line C"<<endl;
            command = 'c';
            break;
        }

}
if(command == 'b')
{
    cout<<"You made it to command line B"<<endl;
    cout<<"Now lets try to make it go back to the MM!"<<endl;
    command = 'a';
}
if (command == 'c')
{
    cout<<"You made it to command line C"<<endl;
}
}

當我輸入b時，我試圖將它輸入，它將輸出到命令行B和另外兩行然后返回主菜單，這是'a'，為什么它不返回主菜單如果命令char等於'a'？

Answer 1

使用switch ：

switch (command) {
case 'a':
    ...
    break;
case 'b':
    ...
    break;
case 'c':
    ...
    break;
default: 
    break;
}

Answer 2

好吧，沒有什么可以告訴你的代碼在第一個條件下回來了。

您可以執行以下操作：

while(true)
{
if(command == 'a'){
    cout<<"At the main Menu, what to do now? Enter H for a list of commands!"<< endl;
    cin>>command;
    switch(command)
    {
        case 'a':
            cout<<"Going to the main menu!"<<endl;
            command = 'a';
            break;
        case 'b':
            cout<<"Going to command line B"<<endl;
            command = 'b';
            break;
        case 'c':
            cout<<"going to command line C"<<endl;
            command = 'c';
            break;
        }

}
if(command == 'b')
{
    cout<<"You made it to command line B"<<endl;
    cout<<"Now lets try to make it go back to the MM!"<<endl;
    command = 'a';
}
if (command == 'c')
{
    cout<<"You made it to command line C"<<endl;
}
}

Answer 3

如果您的主菜單只是頂部的'cout'，然后是另一個cin，那么有兩個解決方案。

您可能一直在考慮的解決方案是將代碼示例包裝在while循環中。

(while command != "c"){ ... }

一旦選擇c，這將結束代碼。 如果玩家專門選擇c，我假設您不想返回主菜單。

使用當前代碼，我對此方法並不十分興奮，因為循環將繼續檢查更新的command變量。 如果您不想在同一命令上無限循環，則必須為每個命令將command狀態設置回'a'。 更好的解決方案是將代碼分離為函數。

舉個例子：

void commandB (){
    cout<<"You made it to command line B"<<endl;
    cout<<"Now lets try to make it go back to the MM!"<<endl;
}

void commandC (){
     cout<<"You made it to command line C"<<endl;
}


int main()
{
    char command = 'a';
    //Monster Goblin;Goblin.HP = 5;Goblin.name = "Goblin";

    while (command != 'c'){
        if(command == 'a'){
            cout<<"At the main Menu, what to do now? Enter H for a list of commands!"<< endl;
            cin>>command;
            switch(command)
            {
                case 'a':
                    cout<<"Going to the main menu!"<<endl;
                    break;
                case 'b':
                    cout<<"Going to command line B"<<endl;
                    commandB(); 
                    command = 'a'; // THIS IS WHAT KEEPS YOU WITHIN THE MM!
                    break;
                case 'c':
                    cout<<"going to command line C"<<endl;
                    commandC();
                    break;
            }

        }
    }
} 

PS：如果變量已經是變量'a'，則沒有理由將命令更改為變量'a'：

（你的代碼）

case 'a':
            cout<<"Going to the main menu!"<<endl;
            command = 'a';
            break;

Answer 4

像這樣的東西可能被認為是好的和清晰的編程風格：

// Function forward-declarations:
void EnterMainMenu();
void EnterCommandLineB();
void EnterCommandLineC();

int main()
{
    Monster Goblin;
    Goblin.HP = 5;
    Goblin.name = "Goblin";
    EnterMainMenu();
}

void EnterMainMenu()
{
    while(true) // Infinite loop
    {
        char command;
        cout<<"At the main Menu, what to do now? Enter H for a list of commands!"<< endl;
        cin>>command;
        switch(command)
        {
            case 'a':
                cout<<"Going to the main menu!"<<endl;
                // Main menu loop will start again after the next line
                break;
            case 'b':
                cout<<"Going to command line B"<<endl;
                EnterCommandLineB();
                break;
            case 'c':
                cout<<"going to command line C"<<endl;
                EnterCommandLineC();
                break;
        }
    }
}

void EnterCommandLineB()
{
    cout<<"You made it to command line B"<<endl;
    cout<<"Now lets try to make it go back to the MM!"<<endl;
}

void EnterCommandLineC()
{
    cout<<"You made it to command line C"<<endl;
}

請注意，在switch語句之后，循環將從頭開始，包括EnterCommandLine函數完成執行時。