Question

noob程序员在这里。如果我提供的信息不够充分，请上大学的第一门CS课并在此处发布第一篇帖子。

仍然试图找出循环。似乎可以得到它，但是一旦循环中存在循环或循环中是否存在语句，我就会被抛弃，也不知道如何进行。对于我的任务，我需要进行以下操作。

您要处理文件中的所有记录吗？（y / n）宽请输入y或n。您要处理文件中的所有记录吗？（y / n）n 输入要处理的记录数：两个 XXXXXXXXXX错误-非数字或负值，请重试输入要处理的记录数：10

这是我的代码：

char a = 0;             //User chooses Y or N
int ProcessAmount = 0;  //Amount of times to process if not all

  cout << "Would you like to process all the records in the file? (y/n) ";
  cin >> a;

  do{

    bool notDone = true;

      if(a  == 'n'){
        while(notDone){
              cout << "Enter records to process: ";
              cin >> ProcessAmount;

              if (cin.fail()){
                  cin.clear();
                  cin.ignore(40,'\n');
                  cout << "" << endl;
              }
              else{
                  notDone = false;  
              }
        }
      }else if(a != 'y' or a != 'n');
            cout <<"Please enter either y or n." << endl;

  }while( a != 'y');

Answer 1

大多数问题都在注释中说明，这是我的解决方法：

char a = 0;             //User chooses Y or N
int ProcessAmount = 0;  //Amount of times to process if not all

cout << "Would you like to process all the records in the file? (y/n) ";
cin >> a;

while (a != 'y') {

  bool notDone = true;

  if(a  == 'n'){
    while(notDone){
      cout << "Enter records to process: ";
      cin >> ProcessAmount;

      if (cin.fail()){
          cin.clear();
          cin.ignore(40,'\n');
          cout << "" << endl;
      } else {
        notDone = false;
      }
    }
  } else if(a != 'y' or a != 'n') {
    cout <<"Please enter either y or n." << endl;
    cin >> a; // Need to get new input because old one is invalid.
  }

};

我也看不到如何使用notDone。另外，我强烈建议您使用适当的缩进，在关键字周围使用空格，例如while，for，if，else，因为这是一种很好的样式。

Answer 2

您只需将y / n请求从循环中移出，那么'a'就永远不会改变其值。看一下您可能想要的更改：

do {
    cout << "Would you like to process all the records in the file? (y/n/f) ";  //f to break the loop
    cin >> a;

    bool notDone = true;

    if (a  == 'n') {
        //. . .
    } else if (a == 'y') {
        //You may want to do something when yes
    } else if (a != 'f')
              cout <<"Please enter either y/n or f." << endl;

} while( a != 'f')

陷入无限循环

2 个答案: