Question

我遇到输入错误的问题。我的输入已经过验证，但我的错误消息“无效范围。请输入范围0-100：”如果输入无效则不显示。

以下是一个例子：

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

您的while()条件应为

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);

}

Answer 2

您正在将do构造与while混合。使用两者都不是。您在while中的测试也没有意义。它可以同时减少和。编辑以下内容，它应该可以正常工作

for(vector<double>::size_type i = 0; i < 15; i++)
    {
        cout << "Please Enter Grade "<< i + 1 <<": " << flush;
        cin >> gradesVector[i];
        while(gradesVector[i] < 0.0 || gradesVector[i] > 100.0); // or not and
        { 
            cout << "Invalid Rage. Please Enter Range 0-100:\n";
                cout << "Please Enter Grade "<< i + 1 <<": " << flush;
                    cin >> gradesVector[i];
        }   
    }

Answer 3

你的状况不对。

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

此外，我只会在矢量有效后将等级添加到矢量中。

在do-while中输入验证

3 个答案: