Chapter 12, Problem 5P

This Practice Program explores how the unnamed namespace works. Listed below are snippets from a program to perform input validation for a username and password. The code to input and validate the username is in a file separate from the code to input and validate the password.

File user.cpp:

namespace Authenticate

{

  void inputUserName()

  {

  do    {

  cout << “Enter your username (8 letters only)” <<

  endl;

  cin >> username;

} while (!isValid());

  }

  string getUserName()

  {

  return username;

  }

}

Define the username variable and the isValid() function in the unnamed namespace so the code will compile. The isValid() function should return true if username contains exactly eight letters. Generate an appropriate header file for this code.

Repeat the same steps for the file password.cpp, placing the password variable and the isValid() function in the unnamed namespace. In this case, the isValid() function should return true if the input password has at least eight characters including at least one nonletter:

File password.cpp:

namespace Authenticate

{

  void inputPassword()

  {

  do    {

  cout << “Enter your password (at least 8 characters “

  <<

  “and at least one nonletter)” << endl;

  cin >> password;

  } while (!isValid());

  }

  string getPassword()

  {

  return password;

  }

}

At this point you should have two functions named isValid(), each in different unnamed namespaces. Place the following main function in an appropriate place. The program should compile and run.

int main()

{

  inputUserName();

  inputPassword();

  cout << “Your username is ” << getUserName() <<

“ and your password is: ” <<

getPassword() << endl;

  return 0;

}

Test the program with several invalid usernames and passwords.