输入被截断

Question

This code looks simple, right?

string password;
cin.ignore();
getline(cin, password);
cout << "The user inputted the password: " << password << endl;

Well for some reason when i type in "secret" as the password the cout results in only "ecret" , ie it is chopping off the first character every time. Why is this?

Answer 1

cin.ignore() ignores the next character of input. That means the s in secret . I imagine the call is there because of previous troubles of getline seeming to skip input (see this question ). This only applies when operator>> is used and leaves a newline beforehand. I recommend instead doing:

getline(std::cin >> std::ws, password);

This will remove troubles over leftover whitespace and not cause problems when there is none.

Answer 2

You can just do this..

string password;
cout << "enter password:";
getline(cin, password);
cout << "The user inputted the password: " << password << endl;

Alternatvely , you can use cin to receive inputs. Now you can use cin.ignore.

string password;
cout << "enter password:";
cin >> password;
cin.clear();
cin.ignore(200, '\n');
cout << "The user inputted the password: " << password << endl;

It is good to use cin.clear() and cin.ignore() when you are receiving inputs using cin >> . However, if you are using getline() , it seems unnecessary to use cin.ignore() .