c++ - do-while 中的输入验证

Question

我遇到输入错误问题。我的输入已通过验证，但如果存在无效输入，我的错误消息“无效范围。请输入范围 0-100:”不会显示。

这是一个例子:

Please Enter Grade 1: 101 (It does not accept input)
Please Enter Grade 1: 321 (It does not accept input)

而不是显示:

Please Enter Grade 1: 101 (It does not accept input)

Invalid Rage. Please Enter Range 0-100.
Please Enter Grade 1: 

这是我的代码:

for(vector<double>::size_type i = 0; i < 15; i++)
  {
    do
    {
         cout << "Please Enter Grade "<< i + 1 <<": " << flush;
            cin >> gradesVector[i];
        }
        while(gradesVector[i] < 0.0 || gradesVector[i] > 100.0);
        { 
            cout << "Invalid Rage. Please Enter Range 0-100:\n";
                cout << "Please Enter Grade "<< i + 1 <<": " << flush;
                    cin >> gradesVector[i];
         }   
}

Answer 1

你的 while()条件应该是

while(gradesVector[i] < 0.0 || gradesVector[i] > 100.0)并使用此代码

for(vector<double>::size_type i = 0; i < 15; i++)
  {
   int c=0;
    do
    {
        if(c!=0)   //checking that we didnt entered loop for first time
          cout << "Invalid Rage. Please Enter Range 0-100:\n";         

           cout << "Please Enter Grade "<< i + 1 <<": " << flush;
           cin >> gradesVector[i];
           c++;   
     }
        while(gradesVector[i] < 0.0 || gradesVector[i] > 100.0);

}