C++ - Limit the string length - c++

Question

I want to create a program that allows the user to create a password and username. However, the password must be between 6 and 10 characters. How would I limit the character input? Also, what if I want the password to include capital letters?
Here's a look at the program so far to give you an idea of what I am trying to do (NOTE: I know the program itself is obviously unfinished but I just want to give you a visual):
#include <iostream>
#include <string>
int main(int argc, const char * argv[]) {
// insert code here...
std::cout << "--------------------------------------------------------------\n";
std::cout << " Welcome to the ECE!! Password Proram!\n";
std::cout << "Username rules: must be 5-10 characters long with no space\n";
std::cout << "Password rules: must be 6+ characters long\n";
std::cout << "Must contain one uppercase letter and one number but no space\n";
std::cout << "--------------------------------------------------------------\n";
//Let's get our password!
std::string username;
std::string password;
const int
//use a do while loop for input validation
do {
std::cout << "Enter your username: ";
std::cin >> username; //add input validation
} while ();
std::cout << "Enter your password:";
std::cin >> password;
return 0;
}

Answer 1

Since you're using std::string, you can use password.size() after getting the user input and checking if the size is within the limits of 5 & 10. If it's not, simply re-query the user for another password. This would be best done in a while loop.
Here is an example of some code from a higher level:
do{
std::cout << "Enter your password:";
std::cin >> password;
}while (password.size() < 6 || password.size() > 10)
You're already doing a similar thing with username, so I was a bit confused on if you meant to be asking about password or not.

Answer 2

To limit character input, you would want to check if the input length is between 6 and 10 characters inclusive. (I don't know of a way to cut off input after 10 characters) You would do something like
start: // A label to direct where the program should go when goto is called.
while(password.length() > 10 || password.length() < 5)
{
std::cout << "The password must be between 5 and 10 characters inclusive." << endl;
std::cin >> password;
}
// To check if there is a capital letter
bool foundUpperLetter = false;
for(int i = 0; i < password.length(); i++)
{
if(foundUpperLetter == true)
break;
if('A' <= password[i] && password[i] <= 'Z')
foundUpperLetter = true;
}
if(!foundUpperLetter)
{
std::cout << "You did not include an uppercase letter in your input. Please try again." << endl;
goto start; // Will make the program go back to label start.
}
You could also add more code to the above section to check for other attributes that the password requires.
Source: 15 months of coding for school and personal enjoyment. Please add your own answer if there is a better way to do something or if you know a way to cut off input after 10 characters

Answer 3

On a conceptual level: you could take in a string input, check the length and other properties (i.e. contains one uppercase letter), use it for further operations. If it does not meet the following criteria, ask the user to re-enter the information.