Why isn't my undo/redo code functioning as required?

Question

I need my undo/redo code to function like the undo/redo features found in Microsoft Notepad, Microsoft Word etc. (I am creating a Word Processor).

Currently, my Undo and Redo code is working to an extent . But there are a number of issues with the undo/redo functions in my application. These are as follows:

If I type a sentence, such as "Hello, my name is Toby.", and then I undo the text (leaving Hello still on the document), I can only redo up to "is".

If I undo all the text in the document, I cannot redo any of the text. So if I again type "Hello, my name is Toby.", and then I undo that line, I cannot then redo any of the text.

I was hoping somebody could help me rectify these issues.

As of now, the code used by both Undo and redo is as follows:

    public struct UndoSection
    {
        public string Undo;
        public int Index;

        public UndoSection(int index, string undo)
        {
            Index = index;
            Undo = undo;
        }
 private void richTextBoxPrintCtrl1_TextChanged(object sender, EventArgs e)
        {
            {
                OldLength = richTextBoxPrintCtrl1.Text.Length; System.Text.RegularExpressions.MatchCollection wordColl = System.Text.RegularExpressions.Regex.Matches(richTextBoxPrintCtrl1.Text, "'?([a-zA-z'-]+)'?");
                counter.Text = wordColl.Count.ToString();
            }
            try
            {
                if (IsRedoUndo == false && (richTextBoxPrintCtrl1.Text.Substring(richTextBoxPrintCtrl1.Text.Length - 1, 1) == " " || richTextBoxPrintCtrl1.Text.Substring(richTextBoxPrintCtrl1.Text.Length - 1, 1) == ","))
                {
                    StackCount = StackCount + 1;
                    RTBRedoUndo[StackCount] = richTextBoxPrintCtrl1.Text;
                }
            }
            catch { }

        }
public string[] RTBRedoUndo;
        public int StackCount = 0;
        public int OldLength = 0;
        public int ChangeToSave = 5;
        public bool IsRedoUndo = false;

        public void RTBTextChanged()
        {
            if (richTextBoxPrintCtrl1.TextLength - OldLength >= ChangeToSave | richTextBoxPrintCtrl1.TextLength - OldLength <= ChangeToSave)
            {
                StackCount += 1;
                RTBRedoUndo[StackCount] = richTextBoxPrintCtrl1.Text;
            }

The undo code:

public void UndoCode()
        {
            IsRedoUndo = true;
            if (StackCount > 0 && RTBRedoUndo[StackCount - 1] != null)
            {
                StackCount = StackCount - 1;
                richTextBoxPrintCtrl1.Text = RTBRedoUndo[StackCount];
            }
        }

The redo code:

public void RedoCode()
        {
            if (IsRedoUndo == false && richTextBoxPrintCtrl1.Text.Substring(richTextBoxPrintCtrl1.Text.Length - 1, 1) == " ")

                IsRedoUndo = true;
            if (StackCount > 0 && RTBRedoUndo[StackCount + 1] != null)
            {
                StackCount = StackCount + 1;
                richTextBoxPrintCtrl1.Text = RTBRedoUndo[StackCount];
            }

I'm not too sure what to try, so I was hoping that somebody with more of a knowledge of programming could help me, as I'm still a novice and in my learning stages.

Thanks :o)

Answer 1

You seem to be setting your stack count back to zero once you Undo. Thats why when u Redo it goes only up to the amount allowed -1 try

Undo Code

public void UndoCode()
    {
        IsRedoUndo = true;
        if (StackCount > 0 && RTBRedoUndo[StackCount] != null)
        {
            StackCount = StackCount - 1;
            richTextBoxPrintCtrl1.Text = RTBRedoUndo[StackCount+1];
        }
    }