want to validate a form (user and password) have default values and want to proceed

[jsos20]

 start_form("get");   #will start the form
        print "What's the User name? ",textfield(-name=>'Username',-value=>'user'),
     #will get the user name
 
    p,  #this gives a new paragraph
 
    "Please enter your password: ",textfield(-name=>'password',-value=>'pass'),
     #will get the password
 
 
#to validate is the problem
 
 
    p;
        if(defined $user && $user eq "") #if the defined value is equal to/or  "blank"  print
        {
 
        print "please enter a value for name",p;
        }
        else
        {
                if(defined $pass && $pass eq "")  #if b's value number is blank print "please enter a value for number
                {
                print "please enter a password",p;
                }
        }
              print hr,
 
    submit('Submit Details for NextScreen');   #will submit when entered
    print hr;
    print hr;
    sub DrawLogin {
    print hr,
          'Username: ',
          textfield( -name=>'user', -default=>'', -size=>15 ),
          p,
          'Password: ',
          password_field( -name=>'pass', -value=>'', -size=>15 ),
          p;
 
    print hr,
          submit( -name=>'next', -value=>'Login' ),
          hr;  # submits user and pass
          end_form();
}
 

have checked if empty but want to check if user entered data to compare against it