Add strings to string array

Question

class Myclass
{
 static string[] user_Name = { "admin", "user1", "user2" };
 static string[] user_Password ={ "admin", "123", "789" };
 public static void Check_Method(string u_name, string u_password)
 {
 for (int i = 0; i < user_Name.Length; i++)
 {
 if (u_name == user_Name[i] && u_password == user_Password[i])
 {
 MessageBox.Show("login successful");
 break;
 }
 else
 {
 if (i == (user_Name.Length - 1))
 MessageBox.Show("Badshow");
 }
 }
 }
 public static void add_user(string name, string password)
 {
 i=user_Name.Length;
 user_Name[i]=name;
 user_Password[i]=password;
 //here i want to add another user but im unable to find the way
 }
}

But it gives an error that it is outside the boundary of an array.

What could be the most convenient way to perform this action?

• Odrade: The reason for the array out of bounds error is that you are using the length of the user name as the index into your user_Name array. This isn't really the meat of the question but I thought you should know.

Answer 1

Don't use arrays if you need variable sized storage.

Use List<string> instead - it allows you to Add items.

---

In your case, your choice of two arrays is questionable, as each user has a corresponding password - always. This suggests that you should have a custom class to hold a user/password pair.

With such a class (say User), you would hold a List<User> and simplify your code.

Answer 2

Try using a List<>.

class Myclass
{
 static List<string> user_Name = new List<string>{ "admin", "user1", "user2" };
 static List<string> user_Password = new List<string>{ "admin", "123", "789" };
 public static void Check_Method(string u_name, string u_password)
 {
 for (int i = 0; i < user_Name.Length; i++)
 {
 if (u_name == user_Name[i] && u_password == user_Password[i])
 {
 MessageBox.Show("login successful");
 break;
 }
 else
 {
 if (i == (user_Name.Length - 1))
 MessageBox.Show("Badshow");
 }
 }
 }
 public static void add_user(string name, string password)
 {
 user_Name.Add(name);
 user_Password.Add(password);
 }
}

Here's a refactored version:

Users are contained in a user class.

They are IEquatable<> which compares their username/passwords (you might want to consider looking into a Guid to keep them unique).

Easily add/remove users.

public class User : IEquatable<User>
{
 public User(string name, string password)
 {
 Name = name;
 Password = password;
 }
 public string Name { get; set; }
 public string Password { get; set; }
 public bool Equals(User other)
 {
 if (other == null) return false;
 return other.Name == Name && other.Password == Password;
 }
}
public class AuthenticationManager
{
 private List<User> LoggedInUsers = new List<User>
 { new User("Admin", "admin"), new User ("user1", "123"), new User ("user2", "789") };
 public bool Authenticate(string userName, string password)
 {
 var user = new User(userName, password);
 //if the user is in the list it will return false otherwise true.
 return !LoggedInUsers.Any(u => user.Equals(user)); 
 }
 public void Login(string name, string password)
 {
 LoggedInUsers.Add(new User(name, password));
 }
 public void Logout(string name, string password)
 {
 LoggedInUsers.Remove(new User(name, password));
 }
}

• Mark Walsh: This would get out of hand pretty quickly. I'd always recommend that newcomers get to grips with OOP concepts ASAP.
• Rehan Manzoor: o great bro... thix ix also a better way

Answer 3

Okay I think you might be thinking about this the wrong way. The way in which you're using arrays is screaming out for an object.

I would made User an object like so

public class User 
{
 public string UserName { get; set;}
 public string Password { get; set;}
}

I would then maintain a list of Users instead. That way you won't need to maintain array indexes and you can easily add new users into the list.

Answer 4

Why don't you use and List and apply a DTO instead of multiples string[] ?

Try something like this:

1) Create a DTO for your Users:

public class UserDTO
{
 public string UserName { get; set; }
 public string Password { get; set; } 
}

2) Use and List<DTO>

class Myclass
{
 static List<UserDTO> users = new List<UserDTO>()
 {
 new UserDTO() { UserName= "admin", Password = "admin" } ,
 new UserDTO() { UserName= "user1", Password = "123" } ,
 new UserDTO() { UserName= "user2", Password = "789" } ,
 }
 public static void Check_Method(string u_name, string u_password)
 {
 if (users.Exists(x => x.UserName == u_name && x.Password == u_password)
 {
 MessageBox.Show("login successful");
 }
 else
 {
 MessageBox.Show("Badshow");
 }
 }
 public static void add_user(string name, string password)
 {
 users.Add(new UserDTO() { UserName= name, Password = password });
 }
}

Answer 5

Try use List<string> class instead of string[]

and add items to array using object.Add() method