Wsrtjtyk

How can I ban a variable from a list without removing it from that list by adding the variable to a list of "banned" variable?

I wish to be able to type in a string. That string is compared to the file names in a folder. If there is a match, the file is read. If I type this same string again, the file should not be read again. There for I want to have a list of "banned" string that is checked whilst typing to avoid the file to be read again.

I have tried a few ways but not getting there. Below is an example of my last attempt.

What would be the best way?

public class test 

{



 string scl= "test3";



 List <string> lsf,lso;



 void Start () 

 {

  lsf=//file names 

   new List<string>();



  lso=//files open 

   new List<string>();



  lsf.Add("test0");

  lsf.Add("test1");

  lsf.Add("test2");

  lsf.Add("test3");

  lsf.Add("test4");



  lso.Add("idhtk49fngo");//random string        

 }



void Update () 

{

 if

 (

  Input.GetKeyDown("a")

 )

 {

  for

  (

   int i=0;

   i<lsf.Count;

   i++

  )

  {

   if(lsf[i]==scl)

   {

    Debug.Log

    (i+" is read");



    for

    (

     int j=0;

     j<lso.Count;

     j++

    )

    {



     //how can i avoid reading

     //lsf[3] here the second time

     //"a" is pressed (by having "test3" 

     //added to a "ban" list (lso) )



     if(scl!=lso[j])

     {



      lso.Add(lsf[i]);



     }

    }

   }

  }

 }

}

Michael’s answer is the way to go here but it can be improved using the more appropriate collection available to keep track of opened files; if you want uniqueness use a set, not a list:

 HashSet<string> openedFiles = new HashSet<string>();



 public static bool TryFirstRead(

     string path,

     out string result)

 {

     if (openedFiles.Add(path))

     {

          result = File.ReadAllText(path);

          return true;

     }



     result = null;

     return false;

 }

Also, I’d avoid throwing vexing exceptions. Give the consumer a friendly way to know if the file was read or not, don’t make them end up having to use exceptions as a flow control mechanism.

I didn't understand although if you want to replace a value from another list.
You can use the list index to create a new list with the values which you removed.
String list1 = {"hi", "hello", "World"};
String list2 = {"bye", "goodbye", "World"};
List1[1] = list2[1];

I would suggest such way:

public static List<string> openedFiles = new List<string>();

public static string ReadFileAndAddToOpenedList(string path)

{

    if (openedFiles.Contains(path))

        throw new Exception("File already opened");

        // Instead of throwing exception you could for example just log this or do something else, like:

        // Consolle.WriteLine("File already opened");

    else

    {

        openedFiles.Add(path);

        return File.ReadAllText(path);

    }

}

The idea is - on every file read, add file to list, so you can check every time you try read file, if it was already read (or opened). If it is, throw exception (or do something else). Else read a file.

You could instead of making it a string list use your own class

public class MyFile

{

    public string Name;

    public bool isOpen;



    public MyFile(string name)

    {

        Name = name;

        isOpen = false;

    }

}



List<MyFile> lsf = new List<MyFile>()

{

    new MyFile("test0"),

    new MyFile("test1"),

    new MyFile("test2"),

    new MyFile("test3"),

    new MyFile("test4")

};

Than when you read the file set isOpen to true

MyFile[someIndex].isOpen = true;

and later you can check this

// E.g. skip in a loop

if(MyFile[someIndex]) continue;

You could than also use Linq in order to get a list of only unread files:

var unreadFiles = lsf.Select(f => f.Name).Where(file => !file.isOpen);