Question

I am currently working on a Windows form application. How can i create the Validation for my password textbox in visual studio (C#) that only allow the text which includes:

• At least one uppercase
• At least one lowercase
• At least one symbol
• Must be above 8 characters

Answer 1

Since its a Windows form application you can do the validation in code as:

string password = textBoxPassword.Text;
if (password.Length > 8 && // Must be above 8 characters
    password.Any(char.IsUpper) && //At least one uppercase
    password.Any(char.IsLower) && //At least one lowercase
    password.Any(char.IsSymbol) //At least one symbol
    )
{
    //Valid password
}
else
{
    //Invalid password
}

You can have this code against Submit button (Button_Click event), or TextBox TextChanging. You can extract it to a method like:

private bool IsValidPassword(string password)
{
    return (password.Length > 8 &&
        password.Any(char.IsUpper) &&
        password.Any(char.IsLower) &&
        password.Any(char.IsSymbol)
        );
}

For example if you want to validate the text on Button_Click then:

private void button1_Click(object sender, EventArgs e)
{
    if(IsValidPassword(textboxPassword.Text))
    {
        //valid password
    }
    else
    {
        //invalid password

    }

}

EDIT:

if you want a digit in the password then you can add one extra check like:

password.Any(char.IsDigit)

To Check for "!@#" Add a check .

password.Any(char.IsPunctuation)