How to make Do function only repeat password input - c++

Question

I finally figured out how to make the function I was looking for, however the issue I am having is I would like to have it only repeat asking for the password input, instead of both the username and password.
#include "stdafx.h"
#include <iostream> // library that contains basic input output functions
#include <string> // library for c++ strings
using namespace std;
int main()
{
//Username and Password to validate credentials
const string USERNAME = "myself";
const string PASSWORD = "stanley";
const string USERNAME2 = "otherperson";
const string PASSWORD2 = "otherpassword";
//strings in which user will enter username and password
string username, password;
int passattempts = 0;
do{
// Prompting user to input username
cout << "Enter Username : ";
cin >> username;
//Checking if username length is less than 4 characters then display an error message
if (username.length() < 4)
{
cout << "Username length must be atleast 4 characters long.";
}
else //if username length is greater than 3
{
//promprting user for password
cout << "Enter Password : ";
cin >> password;
//Checking if password length is less than 6 characters then display an error message
if (password.length() < 6)
{
cout << "Password length must be atleast 6 characters long.";
}
else //if password length is greater than 5
{
//Checking if user's entered credentials are equal to actual USERNAME and PASSWORD
if (username == USERNAME && password == PASSWORD || username == USERNAME2 && password == PASSWORD2)
{
cout << "User credentials are correct!!!" << endl;
break;
}
else
{
cout << "Invalid login details" << endl;
++passattempts;
}
}
}
} while (passattempts != 3);
system("pause");
return (0);
}

Answer 1

Then put the entry (and check on) the username outside the password do loop.
You can always put those inside another do loop if you want to allow the user to re-enter a username that is too short. There's no rule that says you're only allowed one loop :)
something like (pseudo code)
do
{
prompt for username
read username
} while (username invalid)
do
{
prompt for password
read password
} while (password invalid)
There's a philosophical argument to be had about whether or not you tell the user why their data is invalid. I'm not being drawn into that, security people can get a bit... intense.