How can I build a JAVA or C# program which implements a DFA for password

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my DFA shall accept a password of my choice.

my password shall be at least 8 characters long;

It must have a combination of characters (small and capital), digits, and special characters.

For example: my password can be described as follows

1- must be at least 8 characters

2- Must begin wiht the special symbol @

3- Must end with a capital letter

4 Must have at least 2 digits

What I have tried:

i tried to create two dimensional array and fill the row as number of accepted charcter
and the column

Posted 11-Mar-16 8:33am

Abood Almomani

Updated 11-Mar-16 20:12pm

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Patrice T 11-Mar-16 17:22pm

No repost please.

VR Karthikeyan 12-Mar-16 0:27am

What is your problem? Are you having problems in choosing the programming language? or you need ideas about password validation?

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ashwin subramanya · Answer 1 · 2016-03-11T20:12:00

Im assuming DFA here refers to Deterministic Finite Automaton

i think this method should suffice your question

Java

public String validatePassword(String password)
{
   if(password.length<8)
   {
      return "password length less than 8 characters";
   }
   else if(password.charAt(0)!='@')
   {
      return "password must start with a @ character";
   }
   else if(!Character.isUpperCase(password.charAt(password.length)))
  {
      return "Password must end with an Uppercase letter";
  }
  else 
  {
      int noOfDigits=0;
      for(int i=0;i<password.length;i++)>
      {
          if(Character.isDigit(password.charAt(i)))
          {
               noOfDigits++; 
          }
      }
      if(noOfDigits>=2)
      {
          return "password is valid";
      }
      else
      {
          return "password must contain at least 2 digits";
      }
  }
}

Create a String object rather than a 2d char array in java / C#
accept the password and call the above method passing the password to it.