Validate textbox that it should contain one number and a special character

Question

Here Is My C# code:

 private void btnLogin_Click(object sender, EventArgs e)
  {
     if (Regex.IsMatch(txtPassword.Text, @"(!|@|#)"))
      {
      MessageBox.Show("Password Must Contain at least a special character");
       }

       else
       {
     SqlConnection con = new SqlConnection("Data Source=Sumit;Initial Catalog=BroadDB;Integrated Security=True");
    string sql = "select * from tblLogin where username=@username and password=@password";
      SqlCommand cmd = new SqlCommand(sql, con);
      cmd.Parameters.AddWithValue("@username", txtUsername.Text);
      cmd.Parameters.AddWithValue("@password", txtPassword.Text);

   SqlDataAdapter da = new SqlDataAdapter(cmd);

    DataTable dt = new DataTable();
    da.Fill(dt);

    if (dt.Rows.Count > 0)
     {
      Form2 obj = new Form2();
      obj.Show();
     }

   else
    {
      MessageBox.Show("Invalid Data");
    }
  }        
    }

How to validate that password should contain atleast a number and a special character when login button is clicked.

score 1 · Accepted Answer · answered Apr 11 '17 at 08:19

1

try below code

if (!Regex.IsMatch(txtPassword.Text, @"(!|@|#)") || !txtPassword.Text.Any(char.IsDigit))
{
    Console.WriteLine("Password Must Contain at least a special character and digit");
}
else
{
    // DO YOUR STUFF
}

answered Apr 11 '17 at 08:19

Darshan Faldu

1,471
2
15
32

score 0 · Answer 2 · edited May 23 '17 at 10:30

0

Sorry, I can't comment yet, but don't you use a regex for special chars already?

  if (Regex.IsMatch(txtPassword.Text, @"(!|@|#)"))
  {
  MessageBox.Show("Password Must Contain at least a special character");
  }

If I understand your question right you could do this also with numbers or letters.

Have a look on this answered question, it could help you:

How to check if a String contains any letter from a to z?

Update

It's because you don't use a -> ! before Regex.IsMatch, so the MessageBox only Appears when the user inputs a special char, but not when he don't do it.

Try it with this one:

  if (!Regex.IsMatch(txtPassword.Text, @"(!|@|#)"))
  {
  MessageBox.Show("Password Must Contain at least a special character");
  }

edited May 23 '17 at 10:30

Community

1
1

answered Apr 11 '17 at 08:15

Nick77

23
1
12

That Regex code didn't work even if special character not entered its directing to another form and not showing message box – Sumit Bhattarai Apr 11 '17 at 08:18
I don't know if that's the problem, but did you thought about cutting the program when the password is wrong, maybe with this.close() or return? Something like this? Until now your else path is executed every time, does it change the form because of that? – Nick77 Apr 11 '17 at 08:25

score 0 · Answer 3 · answered Apr 11 '17 at 08:17

You can achieve this by testing the string you retrieve from the user input. For this you can best use a regex.

Regex regexPassword = new Regex( @"
  ^               // From the start of the string
  [a-zA-Z0-9!@#]+ // The string should contain some of these characters, like letters including digits and special chars      
  (<=[!@#])       // one of these should be a special character
  (<=[0-9])       // one of these should be a number
  $               // end of string
" , RegexOptions.IgnorePatternWhitespace ) ;

Then of course you can test your regex against your string as usual:

if(regexPassword.IsMatch(yourPasswordString))
{
    //Do what you want
}

Validate textbox that it should contain one number and a special character

3 Answers3

Update