Question

您好我遇到了getline（）的未知问题。我的程序应该是cout一个提示，然后getline（）应该在用户输入中读取但由于某种原因每次我运行它只是couts提示并跳到下一个提示，不允许我输入任何东西。我会发布代码，希望你们能提供一些建议。

int main()
{
    int students = 0;
    students = getStudents(students);

    int quizzes = 0;
    quizzes = getQuizzes(quizzes);

    string studentArray[50];
    int* quizArray = new int[quizzes];
    double* studentAverage = new double[students];
    string studentName = "";
    for(int i = 0; i < students; i++)
    { 
        cout << "Enter the students name: ";
        getline(cin, studentName);
        studentArray[i] = studentName;
        cout << studentName;

        for(int j = 0; j < quizzes; j++)
        {
            cout << "Enter quiz " << j+1 << ":";
            cin >> quizArray[j];
        }
        studentAverage[i] = calculateAvergage(quizArray,quizzes);
        cout << studentArray[i];
        cout << studentName;
    }
    cout << endl;
    cout << "Student              Quiz Average" << endl << endl;
    cout << "---------------------------------" << endl << endl;


    for(int i = 0; i < students; i++)
    {
        cout << studentArray[i];
        cout << setw(10) << studentAverage[i] << endl << endl;
    }   
}
int getStudents(int students)
{
    cout << "How many students?  ";
    cin >> students;
    cout << endl;
    if(students > 50)
    {
        cout << "Invalid number of students, enter a number less than 50: ";
        cin >> students;
        cout << endl;
    }
    return students;
}
int getQuizzes(int quizzes)
{
    cout << "How many quizzes?  ";
    cin >> quizzes;
    cout << endl;
    if(quizzes > 10)
    {
        cout << "Invalid number of quizzes, enter a number less than 10: ";
        cin >> quizzes;
        cout << endl;
    }
    return quizzes;
}
double calculateAvergage(int quiz_array[],int num_quizzes)
{
    double average = 0;
    for(int i = 0; i < num_quizzes; i++)
    {
        average = quiz_array[i] + average;
    }
    average = (average/num_quizzes);
    return average;
}

Answer 1

从像这样的流中读取单个值

cin >> quizzes;

不消耗行尾字符（或尝试阅读quizzes后遗留的任何其他无效字符），因此下一次调用getline将继续从同一行读取输入（通常你会看到在阅读quizzes后该行为空，所以getline最终没有读到任何内容。）

如果在阅读quizzes后使用以下内容，您的计划应该有效：

std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');

或者您只需以与其他值相同的方式阅读studentName

std::cin >> studentName;

与对operator>>的所有调用一样，这会删除所有前导空格，包括换行符。

getline（）没有按预期工作

1 个答案: