第二次运行时出错

Question

第一次程序运行正常，但是第二次它没有从用户输入字符串，我不知道为什么？

我认为getline(cin,str);中存在问题，但我无法解决问题

#include<iostream>
#include<string>

using namespace std;

int main(){
    string str;
    char check;
    do{
        system("cls");
        cout<<"Enter the number (sample : +92121234567(Must contain 12 characters)) : ";
        getline(cin,str);
        cout<<endl<<str;
    if(str.length() == 12){

        string countrycode = str.substr(0,3);

        if(countrycode == "+92"){

            string citycode = str.substr(3,2);

            if(citycode == "51"){
                cout<<endl<<"This number belongs to Islamabad";
            }else if(citycode == "42"){
                cout<<endl<<"This number belongs to Lahore";
            }else if(citycode == "21"){
                cout<<endl<<"This number belongs to Karachi";
            }else{
                cout<<endl<<"Unknown Number";
                cout<<endl<<"Remarks : ";
                cout<<endl<<"Unknown city code";
            }
        }else{
            if(str.substr(0,1) =="-"){
                cout<<endl<<"Unknown Number";
                cout<<endl<<"Remarks : ";
                cout<<endl<<"Wrong country code format";    
            }
            if(str.substr(1,2) !="92"){
                cout<<endl<<"Unknown Number";
                cout<<endl<<"Remarks : ";
                cout<<endl<<"Unknown country code"; 
            }   
        }
    }else{
        cout<<endl<<"Unknown Number";
        cout<<endl<<"Remarks : ";
        cout<<endl<<"Number is over 12 characters";
    }


    cout<<endl<<"Do you want to enter another number (y/n): ";
    cin>>check;
    //str.clear();
}while(check=='y'||check=='Y');

cout<<endl<<"End of Program. Bye!"<<endl;
system("pause");
return 0;

}

Answer 1

使用cin >> str; 不知道为什么，但是getline对我也不起作用。