C++嵌套验证循环

Question

我的老师希望我在玩家的选择中放置一个“嵌套验证循环”，这样可以保持循环，直到他们输入有效的输入（1,2或3）。我无法获得任何工作，我可以得到一些指示，请和谢谢。

#include <iostream> 
#include <ctime> 
#include <string> 
using namespace std; 

// Keaton Graffis 12/28/2015 

int main() 
{ 
    int seed = time(0); 
    srand(seed); 
    char playAgain; 
    int playerChoice, aiChoice, win = 0, tie = 0, lose = 0; 
    do 
    { 
     cout << "Lets play a game of rock paper scissors.\n"; 
     cout << "Enter a 1 for sccisors a 2 for rock or a 3 for paper: "; 

     // Generates outcomes of the players choice 
     cin >> playerChoice; 
     if (playerChoice == 1) 
     { 
      cout << "You picked Rock!\n"; 
     } 
     else if (playerChoice == 2) 
     { 
      cout << "You picked Paper!\n"; 
     } 
     else if (playerChoice == 3) 
     { 
      cout << "You picked Scissors!\n"; 
     } 

     // gentrate the computers choices 
     int aiChoice = rand() % 3 + 1; 

     if (aiChoice == 1) 
     { 
      cout << "The computer chose Rock!\n"; 
     } 

     else if (aiChoice == 2) 
     { 
      cout << "The computer chose Paper!\n"; 
     } 
     else if (aiChoice == 3) 
     { 
      cout << "The computer chose Scissors!\n"; 
     } 

     // Determines wins, ties and loses 
     if (playerChoice == 1 && aiChoice == 1) { 
      cout << "Rock meets Rock its a tie!" << endl; 
      tie++; 
     } 
     else if (playerChoice == 1 && aiChoice == 2) 
     { 
      cout << "Rock is covered by Paper the computer wins!." << endl; 
      lose++; 
     } 
     else if (playerChoice == 1 && aiChoice == 3) 
     { 
      cout << "Rock crushes Scissors you win!" << endl; 
      win++; 
     } 
     else if (playerChoice == 2 && aiChoice == 1) 
     { 
      cout << "Paper covers Rock you win!" << endl; 
      win++; 
     } 
     else if (playerChoice == 2 && aiChoice == 2) 
     { 
      cout << "Paper meets Paper its a tie!" << endl; 
      tie++; 
     } 
     else if (playerChoice == 2 && aiChoice == 3) 
     { 
      cout << "Paper is cut by Scissors the computer wins!" << endl; 
      lose++; 
     } 
     else if (playerChoice == 3 && aiChoice == 1) 
     { 
      cout << "Scissors are crushed by Rock computer wins!" << endl; 
      lose++; 
     } 
     else if (playerChoice == 3 && aiChoice == 2) 
     { 
      cout << "Scissors cuts Paper you win!" << endl; 
      win++; 
     } 
     else if (playerChoice == 3 && aiChoice == 3) 
     { 
      cout << "Scissors meet Scissors its a tie!" << endl; 
      tie++; 
     } 

     // Outputs wins, ties and loses 
     cout << "Wins: " << win << endl; 
     cout << "Ties:" << tie << endl; 
     cout << "Losses:" << lose << endl; 
     cout << "Would you like to play again? Y/N" << endl; 
     cin >> playAgain; 
     system("CLS"); 
     // Allow user to play again 
    } while (playAgain == 'Y' || playAgain == 'y'); 
} 

Answer 1

您可以在接收有效输入时读入输入并从循环中断开的代码块上放置一个while循环。

int choice; 
bool valid = false; 

while(!valid) { 
    cout << "Enter a 1 for scissors, 2 for rock, 3 for paper" << endl; 
    cin >> choice; 
    if(choice == 1 || choice == 2 || choice == 3) 
     valid = true; 
}