How Do I Convert String to String Array In List.Add?

Hello! I’m working with a password system for “Computers” in my game. I want to make it so you can add and save passwords to the system. After a lot of tedious work, I got to a point where I use string.Join to turn my list of strings into one string. I then load my string, where I want to split it and turn it into a list. I will then use that list and set the list of codes. The only issue is I can’t split the string in the List.Add function, and I don’t believe I can add an array to a list. If anyone could help, here is the code:
private const string seperator = “!SEPARATE_VALUES!”;

public GameObject disableSelf;
public GameObject loadNextOne;
public GameObject loadNextTen;

// Stored Strings
public List<string> codesLvlOne;
public List<string> codesLvlTwo;
public List<string> codesLvlThree;
public List<string> codesLvlFour;
public List<string> codesLvlFive;
public List<string> codesLvlSix;
public List<string> codesLvlSeven;
public List<string> codesLvlEight;
public List<string> codesLvlNine;
public List<string> codesLvlTen;

//Load Strings
private List<string> codesLOne;
private int i = 0;

void Start () {
	string CodesOne = File.ReadAllText(Application.dataPath + "/SaveData/passwordListOne.txt");

	string[] splitCodesOne = CodesOne.Split(new[] { seperator }, System.StringSplitOptions.None)

	while (i <= splitCodesOne.Length) {
  •   	i++;*
  •   }*
  • }*
  • void OnApplicationQuit () {*
  •   SavePasswords();*
  • }*
  • public static void SavePasswords () {*
  •   List<string> CodesLOne = string.Join(seperator, codesLvlOne);*
  •   File.WriteAllText(Application.dataPath + "/SaveData/passwordListOne.txt", CodesLOne);*
  • }*

@ecv80 Thanks for the help! I was able to condense my work, even though I figured out I forgot a semicolon! Sorry if I was too vague with the issue, even if you helped anyway. The editor now says:

The best overloaded method match for string.Join(string, string) has some invalid arguments

I tried adding the .ToArray() function to the saving part, but it keeps saying:

Argument #2 cannot convert string expression to type string
Please help!
,@ecv80 Thanks so much! I figured out that I was missing a semicolon right above the while statement! I managed to shrink my code using the List.AddRange function! Sorry if I was a bit vague on the issue. Now in the editor, there is a console error saying: “The best overloaded method match for `string.Join(string, string)’ has some invalid arguments”. Any idea how to fix this?