Validating a password with c++ and giving specific errors - c++

Question

I am trying to write a c++ program that validates a password that requires one uppercase letter, one lowercase letter, and a digit using functions.
The issue is that I'm trying to display the specific errors that are occurring, not just "Invalid, try again.", but I'm having a hard time figuring out how to do that. It should keep asking until they enter a valid password.
#include<iostream>
#include<string>
#include<cctype>
using namespace std;
int validate(string);
string find(int);
int main()
{
string pw;
int val;
string result;
do{
cout << "Enter password: " << endl;
cin >> pw;
val = validate(pw);
cout << find(val) << endl;
} while (val != 0);
}
//VALIDATES PASSWORD
int validate(string pw)
{
int valid = 0;
char c;
int length = pw.length();
bool digit = false;
bool upper = false;
bool lower = false;
int i = 0;
if (pw.length() < 6)
valid = 1;
while (i < pw.length())
{
c = pw[i];
i++;
if (isdigit(c))
{
digit = true;
valid++;
}
if (isupper(c))
{
upper = true;
valid++;
}
if (islower(c))
{
lower = true;
valid++;
}
//Valid input
if (length >= 6 && upper && lower && digit)
valid = 0;
}
return valid;
}
//RETURNS STRING WITH PROBLEM
string find(int valid)
{
string result;
if (valid == 0)
{
result = "Valid Password ";
}
else
{
result = "Invalid Password: ";
if (valid == 1)
result = result + " Too short ";
else if (valid == 2)
result = result + " too short, needs a digit, and an uppercase letter";
else if (valid == 3)
result = result + " too short, needs a digit, and a lowercase letter";
else if (valid == 4)
result = result + " too short, and needs an uppercase letter";
else if (valid == 5)
result = result + " too short, and needs a lowercase letter";
else if (valid == 6)
result = result + " too short, needs a digit";
else if (valid == 7)
result = result + " Needs a didgit ";
else if (valid == 8)
result = result + " Needs digit and uppercase letter ";
else if (valid == 9)
result = result + " Needs digit and lowercase letter";
else if (valid == 10)
result = result + " Needs an uppercase letter ";
else if (valid == 11)
result = result + " Needs uppercase and lowercase letter";
else if (valid == 12)
result = result + " Needs a lowercase letter";
}
return result;
}

Answer 1

I think you are confusing the number of characters (valid) and the type of error -
else if (valid == 9)
result = result + " Needs digit and lowercase letter";
could be produced from 123456abc
As valid == 9 really only counts the characters in the set. Separate counting and whether character classes are used.

Answer 2

It's better to use some flags (bool variables) instead of one number.
If you want to use one number, you must create 2^(things to check) situations
using that number. Here 2^4 = 16 situations is required.
One of the easiest way to mix flags in one number is this:
nth digit = nth flag
for example use this order (length, lower, upper, digit).
So,
to set length validity, add 1000 to number;
to set lower validity, add 100 to number;
to set upper validity, add 10 to number;
to set digit validity, add 1 to number;
Now,
((number)%10 == 1) means digit validity
((number/10)%10 == 1) means upper validity
((number/100)%10 == 1) means lower validity
((number/1000)%10 == 1) means length validity
Following code uses separate flags:
#include<iostream>
#include<string>
using namespace std;
class PasswordStatus
{
bool len, low, up, dig;
//============
public:
PasswordStatus()
{
len = low = up = dig = false;
}
//-----------
void ShowStatus()
{
cout << endl << "Password Status:" << endl;
cout << "Length : " << (len ? "OK" : "Too Short") << endl;
cout << "Contains Lower Case : " << (low ? "Yes" : "No") << endl;
cout << "Contains Upper Case : " << (up ? "Yes" : "No") << endl;
cout << "Contains Digit : " << (dig ? "Yes" : "No") << endl;
}
//-----------
void checkValidity(string pass)
{
int sLen = pass.length();
len = (sLen >= 6);
for(int i = 0; i<sLen; i++)
{
char c = pass[i];
if(!low && islower(c)) {low = true; continue;}
if(!up && isupper(c)) {up = true; continue;}
if(!dig && isdigit(c)) {dig = true; continue;}
}
}
//-----------
bool IsTotalyValid()
{
return low && up && dig && len;
}
};
//====================================================================
int main()
{
PasswordStatus ps;
string pw;
do
{
cout << endl << "Enter password: " << endl;
cin >> pw;
ps.checkValidity(pw);
ps.ShowStatus();
} while (!ps.IsTotalyValid());
cout << "Valid Password : " << pw;
return 0;
}