如何解决C++代码片段cin.getline的运行时跳过问题

Question

#include<conio.h> 
#include<iostream> 
using namespace std; 

class Student 
{ 
private: 
char name[20]; 
char rollno[20]; 

public: 
void input(); 
void display(); 
}; 
class Acadamic_details:public Student 
{ 
private: 
    float marks,percentage; 
public: 
    void input(); 
    void display(); 
}; 
    class Guardian_details:public Acadamic_details 
    { 
    private: 
     char F_name[20],M_name[20]; 
    public: 
     void input(); 
     void display(); 
    }; 

    void Student::input() 
    { 
    cout<<endl<<" Enter the Name : "; 
    cin.getline(name,30,'\n'); 
    cout<<endl<<" Enter the Roll No :"; 
    cin.getline(rollno,30,'\n'); 
    } 
    void Acadamic_details::input() 
    { 
    Student::input(); 
    cout<<endl<<" Enter the Marks out of 500 :"; 
    cin>>marks; 
    } 
    void Guardian_details::input() 
    { 
     Acadamic_details::input(); 
     cout<<endl<<" Enter the Father's Name :"; 
     cin.getline(F_name,30,'\n'); 
     cout<<endl<<" Enter the Mother's Name :"; 
     cin.getline(M_name,30,'\n'); 
    } 

    void Student::display() 
    { 
    cout<<endl<<" Name : "<<name<<endl; 
    cout<<" Roll No : "<<rollno<<endl; 
    } 
    void Acadamic_details::display() 
    { 
     Student::display(); 
     percentage=(marks/500)*100; 
     cout<<endl<<" Marks : "<<marks<<"/500"<<endl; 
     cout<<" Percentage : "<<percentage<<"%"<<endl; 
    } 
      void Guardian_details::display() 
      { 
       Acadamic_details::display(); 
       cout<<endl<<" Father's Name : "<<F_name<<endl; 
       cout<<" Mother's Name : "<<M_name<<endl; 
      } 

    int main() 
    { 
    Guardian_details g1; 
    cout<<" Enter the Student's Details "<<endl; 
    g1.input(); 
    cout<<" Student's Details Are : "<<endl; 
    g1.display(); 
    getch(); 
    return 0; 
    } 

这是多级继承的实现。 编译期间没有编译错误。 但是当我执行的程序，我面临着一个运行时间问题

void Guardian_details::input() 
{ 
    Acadamic_details::input(); 
    cout<<endl<<" Enter the Father's Name :"; 
    cin.getline(F_name,30,'\n'); 
    cout<<endl<<" Enter the Mother's Name :"; 
    cin.getline(M_name,30,'\n'); 
} 

从上面的代码段，cin.getline(F_name,30,'\n');不工作。 每次运行程序它直接执行cout<<endl<<" Enter the Mother's Name :"; cin.getline(M_name,30,'\n');

跳过cin.getline(F_name,30,'\n');。

这里是输出画面：

谁能解释为什么发生得如此，什么是替代该代码。

在此先感谢。

Answer 1

在Acadamic_details::input当你做

cin>>marks; 

新行留在缓冲区下次调用getline，其解释为一个空行。