#include <windows.h>
#include <iostream>
#include "tchar.h"
 
int main(void);
TCHAR readKey(void);
TCHAR *getPassword(TCHAR *buffer, int length);
 

int main(void)
{
  TCHAR *password;
  const int MAX_DIGITS = 10; // number of digits allowed in password
  std::cout << "Please enter your password: ";
  password = getPassword(NULL, MAX_DIGITS);
  std::cout << "\n\nYour password is \"" << password << "\".\n\n";
  std::cout << "Done, hit a key to exit."<< std::flush;
  readKey();
  return 0;
}
 

// reads a key, returning its ASCII or Unicode value.  clears the input buffer
// prior to reading a key, so will block until new keyboard input is received.
TCHAR readKey(void)
{
  INPUT_RECORD input;
  DWORD count;
  FlushConsoleInputBuffer(GetStdHandle(STD_INPUT_HANDLE));
  do
  {
	ReadConsoleInput(GetStdHandle(STD_INPUT_HANDLE), &input, 1, &count);
  } while((input.EventType != KEY_EVENT) || (!input.Event.KeyEvent.bKeyDown) || (!input.Event.KeyEvent.uChar.UnicodeChar));
  return (TCHAR)input.Event.KeyEvent.uChar.AsciiChar;
}
 

// retrieves a password, masking entered digits with an asterisk.  buffer
// may be supplied by the caller, or allocated automagically by passing NULL.
TCHAR *getPassword(TCHAR *buffer, int length)
{
  TCHAR key;
  int position = 0;
  
  if(!buffer)  // if buffer is NULL, allocate space
	buffer = new TCHAR[length+1];
  do
  {
	key = readKey();
	switch(key)
	{
	  case '\b': // backspace
		if(position > 0)
		{
		  buffer[--position] = 0;
		  std::cout << "\b \b";  // do a 'destructive' backspace
		}
		break;
	  case '\n': // enter/return
	  case '\r':
		break;
	  default:
		if(position < length)
		{
		  buffer[position++] = key;
		  std::cout << '*';
		}
	}
  } while(key != '\n' && key != '\r'); // loop until user hits enter/return
  return buffer;
}