为什么不能输入标题？？

#include<iostream>
#include<string>
using namespace std;
class Publication{
    protected:
        string title;
        float price;
    public:
        Publication(string ti,float pri):title(ti),price(pri)
        {
        
        }
        void GetData(){
            string tit;
            float pri;
            cout<<"输入标题："<<endl;
            getline(cin,tit);
            
            cout<<"输入价格"<<endl;
            cin>>pri;
            Settitle(tit);
            Set_price(pri);   
            
        }
        void Settitle(string ti){
            title=ti;
            
        }
        void Set_price(float pri){price=pri;
        }
        void Show(){
            cout<<"标题："<<title<<endl;
            cout<<"价格："<<price<<"元"<<endl;
        }
        ~Publication(){
        }
};
class Book:public Publication
{
    protected:
        int page;
    public:
        Book(string ti="",float pri=0,int pa=0):Publication(ti,pri),page(pa){
        }
        
        void GetData(){
            Publication::GetData();
            cout<<"输入页数："<<endl;
            int pa;
            cin>>pa;
            Set_page(pa);            
        }
        void Set_page(int pa){
            page=pa;
        }
        void Show(){
            Publication::Show();
            cout<<"页数："<<page<<"页"<<endl;
        }
        ~Book(){
        }
};
class Tape:public Publication
{
    protected:
        float playtime;
    public:
        Tape(string ti="",float pri=0,float playt=0):Publication(ti,pri),playtime(playt){
        }
        void GetData(){
            Publication::GetData();
            cout<<"输入播放时间："<<endl;
            float playt;
            cin>>playt;
            playtime=playt;
        }
        void Show(){
            Publication::Show();
            cout<<"播放时间："<<playtime<<"分钟"<<endl;
        }
};
 
int main(){
    cout<<"建立书籍"<<endl;
    Book b1;
    string str;
    b1.GetData();
    b1.Show();
//    cout<<"重新输入标题："<<endl;     //有问题，不能重新输入标题
   
//    getline(cin,str);
//    b1.Settitle(str);
//    b1.Show();
   
    cout<<"建立磁带"<<endl;//也不能输入标题
    Tape t1;
    t1.GetData();
    t1.Show();
    return 0;
}