gets(） 不接受输入

我有一些大学工作，因为我注意到gets（）不起作用，但我无法弄清楚为什么。

我尝试将 getch（） 和 getchar（） 放在 gets（） 之前，但还有其他问题。

当我在do-while（标记为-----> 3）之前编写实现gets（）的代码时，它可以工作!!

有人可以帮助我吗？

#include<iostream>
#include<stdio.h>
#include<conio.h>
using namespace std;
class student
{
    int rollNo;
    char department[20];
    int year;
    int semester;
public:
    student()
    {
        rollNo=0;
        year=0;
        semester=0;
    }
    void getData();
    void promote();
    void changeDepartment();
    void display();
};
void student::changeDepartment()
{
    if(rollNo!=0)
    {
        cout<<"nEnter the new Departmentn";
        gets(department);                                 -------------->1
    }
    else
    {
        cout<<"nStudent not confirmedn";
    }
}
void student::getData()
{
    cout<<"nEnter the roll non";
    cin>>rollNo;
    cout<<"nEnter the yearn";
    cin>>year;
    cout<<"nEnter the semestern";
    cin>>semester;
    cout<<"nEnter the departmentn";
    gets(department);                                  ----------------> 2
}
void student::promote()
{
    if(rollNo!=0)
    {
        semester+=1;
        if(semester%2==1)
        {
            year+=1;
        }
    }
    else
    {
        cout<<"nStudent not confirmedn";
    }
}
void student::display()
{
    if(rollNo!=0)
    {
        cout<<"nRoll No : "<<rollNo;
        cout<<"nYear : "<<year;
        cout<<"nSemester : "<<semester;
        cout<<"nDepartment : "<<department;
    }
    else
    {
        cout<<"nStudent not confirmed";
    }
}
int main()
{
    student s;
    int ch;
    char choice;
                                                      ----------------> 3
    do
    {
        cout<<"nMain Menu";
        cout<<"n1. Enter student details";
        cout<<"n2. Change department of student ";
        cout<<"n3. Promote student ";
        cout<<"n4. Display student details ";
        cout<<"nEnter your choice ";
        cin>>ch;
        switch(ch)
        {
            case 1 : s.getData();
                     s.display();
                        break;
            case 2 : s.changeDepartment();
                     s.display();
                        break;
            case 3 : s.promote();
                     s.display();
                        break;
            case 4 : s.display();
                        break;
        }
        cout<<"nDo you want to continue? (Y/n)n";
        cin>>choice;
    }while((choice=='y')||(choice=='Y'));
    return(0);
}