困惑为什么这个主不工作

Question

好吧，所以我想写一个主要的地方，它会要求用户输入一个数字1到6，如果数字是6，它会结束程序。如果它高于6，它会要求重新输入号码。事情是，当我运行它，它不会检查“if”语句，并自动去这条线“请输入另一个选项”

任何想法，为什么我的程序会做这样的事情？

更新：我在说它会自动跳过所有的if语句，并询问while循环中的最后一个问题。

int main() 
{ 
    int userChoice = 0; 

    print(); //printing all of the options. 

    cout << "Please enter one of the options listed below" <<endl; 
    cin >> userChoice; 

    while(userChoice != 6)// 6 = the user wishing the end the program when they press 6. 
    { 
     if(userChoice == 1) //adding integer to the front of the list 
     { 
      addValueFront(); 
     } 
     else if(userChoice == 2)//adding integer to the back of the list 
     { 
      addValueBack(); 
     } 
     else if(userChoice == 3)//removing from the list 
     { 
      int n = 0; 
      cout << "Please enter the integer you wish to remove" << endl; 
      cin >> n; 
      removeValue(n); 
     } 
     else if(userChoice == 4)//printing the list 
     { 
      printList(); 
     } 
     else if(userChoice == 5)//printing the number of items from the list 
     { 
      printItem(); 
     } 

     else 
     { 
      cout << "The number you have entered is too high. Please try again" << endl; 
      cin >> userChoice; 
     } 
     cout << "please enter another option" <<endl; 

     cin >> userChoice; //sets up which option the user can choose from. 
    } 
} 

Answer 1

我认为下面的程序是你想要什么：

int main()                  
{                    
    int userChoice = 0;               

    print(); //printing all of the options.          

    cout << "Please enter one of the options listed below" <<endl;                         
    do // 6 = the user wishing the end the program when they press 6.     
    {                    
    cin >> userChoice; 
    if(userChoice > 6)              
    {                  
     cout << "The number you have entered is too high. Please try again" << endl; 
     cout << "please enter another option" <<endl;       
    }                  
    else if(userChoice == 1) //adding integer to the front of the list   
    {                   
     addValueFront();               
    }                   
    else if(userChoice == 2)//adding integer to the back of the list   
    { 
     addValueBack();               
    } 
    else if(userChoice == 3)//removing from the list       
    { 
     int n = 0;                
     cout << "Please enter the integer you wish to remove" << endl;   
     cin >> n;                 
     removeValue(n);               
    }                   
    else if(userChoice == 4)//printing the list         
    {                   
     printList();                
    }                   
    else if(userChoice == 5)//printing the number of items from the list  
    {                   
     printItem();                
    }                   
    } while(userChoice != 6);              
}                    

Answer 2

在您的else块的末尾添加“continue”。

cout << "The number you have entered is too high. Please try again" << endl; 
cin >> userChoice; 
continue; 

Answer 3

请参考答案为this question和this question。您需要在每个cin < <之前调用cin.clear（）和cin.ignore（），以刷新键盘缓冲区，以便它的行为正确且一致。

另外，你应该从else块中删除cin，因为它在逻辑上是不正确的。

Answer 4

使用开关这将是更好的选择。

int main() 
{ 
    int userChoice = 0; 

    print(); //printing all of the options. 

    cout << "Please enter one of the options listed below" <<endl; 
    cin >> userChoice; 

    while(1)// 6 = the user wishing the end the program when they press 6. 
    { 
     if(userChoice == 1) //adding integer to the front of the list 
     { 
      addValueFront(); 
     } 
     else if(userChoice == 2)//adding integer to the back of the list 
     { 
      addValueBack(); 
     } 
     else if(userChoice == 3)//removing from the list 
     { 
      int n = 0; 
      cout << "Please enter the integer you wish to remove" << endl; 
      cin >> n; 
      removeValue(n); 
     } 
     else if(userChoice == 4)//printing the list 
     { 
      printList(); 
     } 
     else if(userChoice == 5)//printing the number of items from the list 
     { 
      printItem(); 
     } 
     else if(userChoice == 6)// 6 = the user wishing the end the program when they press 6. 
     { 
      return 0; 
     } 
     else 
     { 
      cout << "The number you have entered is too high. Please try again" << endl; 
      cin >> userChoice; 
     } 
    } 
}