Visual C#: k9pad – notepad clone with 9 tabs

I was playing with Visual C# 2015 Community Edition lately and decided to make a simple text editor. I’ve spent a lot of time actually, trying to find how to print, print preview, get the cursor (caret) position etc… Find and Replace were also challenging. The program allows you to drag and drop and if you associate the text file to the EXE, you can double-click on any TXT file and it will be opened in k9pad. There are probably some minor bugs here and there, but it works fine for me… For now. If i see any bugs, I’ll try to fix them (if I don’t move to something more exciting).

git clone http://www.github.com/klimenta/k9pad

or download the source from here or just the executable from EXE. 7zip is required.

/*

Notepad clone with 9 tabs for text.
K.Andreev - 2016, Simplified BSD license

*/

using System;
using System.Drawing;
using System.Windows.Forms;
using System.IO;
using System.Drawing.Printing;

namespace k9pad
{
    public partial class Form1 : Form
    {
        //Array of TabPage controls that are containers for the text boxes
        private TabPage[] arrTabPage = new TabPage[9];
        //Array of textbox controls, one for each tab
        public static TextBox[] arrTextBox = new TextBox[9];
        //Array of strings for each tab that holds the filename for each text file
        private string[] strFileName = new string[9];
        //Array of boolean for each tab if the content has changed in any text
        private bool[] bChanged = new bool[9];
        //Temp varaible 
        public static int intCounter = 0;
        //For printing
        private PrintDocument printDoc = new PrintDocument();
        private PageSettings pgSettings = new PageSettings();
        private PrinterSettings prtSettings = new PrinterSettings();
        private string strToPrint;

        public Form1()
        {
            InitializeComponent();            
            //Initialize status line info
            for (int i = 0; i > strFileName.GetLength(0); i++)
            {
                strFileName[i] = null;
                bChanged[i] = false;
            }
            //Create each tab page and change the properties
            for (int i = 0; i < arrTabPage.GetLength(0); i++)
            {                
                intCounter = i + 1;
                arrTabPage[i] = new TabPage();
                arrTabPage[i].Name = "tabPage" + intCounter.ToString();
                arrTabPage[i].Text = intCounter.ToString();
                tabControl1.TabPages.Add(arrTabPage[i]);
                arrTabPage[i].Parent = tabControl1;
                arrTabPage[i].Dock = DockStyle.Fill;
            }
            //Create each text box and change the properties
            for (int i = 0; i < arrTextBox.GetLength(0); i++)
            {
                intCounter = i + 1;
                arrTextBox[i] = new TextBox();
                arrTextBox[i].Text = arrTextBox[i].Name;
                arrTabPage[i].Controls.Add(arrTextBox[i]);
                arrTextBox[i].Multiline = true;
                arrTextBox[i].MaxLength = 0;
                arrTextBox[i].AcceptsTab = true;
                arrTextBox[i].AllowDrop = true;
                arrTextBox[i].WordWrap = true;
                arrTextBox[i].ScrollBars = ScrollBars.Both;
                arrTextBox[i].Dock = DockStyle.Fill;
                arrTextBox[i].Font = new Font("Courier New", 10, FontStyle.Regular);
                arrTextBox[i].TextChanged += new EventHandler(Text_Changed);
                arrTextBox[i].KeyUp += new KeyEventHandler(Key_Up);
                arrTextBox[i].DragEnter += new DragEventHandler(TextBox_DragEnter);
                arrTextBox[i].DragDrop += new DragEventHandler(TextBox_DragDrop);                
            }
            arrTextBox[0].Select();
            arrTextBox[0].Focus();
            //Update status labels at the bottom
            toolStripStatusLabelFontName.Text = "FTN: " + fontDialog1.Font.Name;
            toolStripStatusLabelFontSize.Text = "FTS: " + fontDialog1.Font.Size;
            toolStripStatusLabelFileChanged.Text = "FC: F";
            //Attach the print handler
            printDoc.PrintPage += new PrintPageEventHandler(printDoc_PrintPage);
            //Get command line args - used when you double click a text file            
            string[] args = Environment.GetCommandLineArgs();
            //Return if no input argument
            if (args.Length != 2) return;
            try
            {
                if (args[1] != null && args[1].Length > 0)
                {
                    if (File.Exists(args[1]))
                    {
                        intCounter = 0;
                        myOpenFile(args[1]);
                    }
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error: " + ex.Message, "File Open");
            }            
        }

        //Allow drag & drop to open a file
        private void TextBox_DragDrop(object sender, DragEventArgs e)
        {
            intCounter = tabControl1.SelectedIndex;
            string[] files = (string[])e.Data.GetData(DataFormats.FileDrop);
            if (files != null && files.Length != 0)
            {
                myOpenFile(files[0]);
            }
        }

        private void TextBox_DragEnter(object sender, DragEventArgs e)
        {
            if (e.Data.GetDataPresent(DataFormats.FileDrop, false))
                e.Effect = DragDropEffects.All;
        }

        //Update the status line when the text changes
        protected void Text_Changed(object sender, EventArgs e)
        {
            //Get the current tab
            intCounter = tabControl1.SelectedIndex;
            bChanged[intCounter] = true;
            toolStripStatusLabelFileChanged.Text = "FC: T";
            //Get the current carret position (text cursor)
            int intLine = arrTextBox[intCounter].GetLineFromCharIndex(arrTextBox[intCounter].SelectionStart);
            int intColumn = arrTextBox[intCounter].SelectionStart - 
                arrTextBox[intCounter].GetFirstCharIndexFromLine(intLine);
            intLine++;
            intColumn++;
            toolStripStatusLabelLine.Text = "LN: " + intLine.ToString();
            toolStripStatusLabelColumn.Text = "CO: " + intColumn.ToString();
        }

        //Update status when a key is released
        protected void Key_Up(object sender, KeyEventArgs e)
        {
            intCounter = tabControl1.SelectedIndex;
            int intLine = arrTextBox[intCounter].GetLineFromCharIndex(arrTextBox[intCounter].SelectionStart);
            int intColumn = arrTextBox[intCounter].SelectionStart - 
                arrTextBox[intCounter].GetFirstCharIndexFromLine(intLine);
            intLine++;
            intColumn++;
            toolStripStatusLabelLine.Text = "LN: " + intLine.ToString();
            toolStripStatusLabelColumn.Text = "CO: " + intColumn.ToString();
            //Switch tab when CTRL + 1, 2, 3 etc is pressed
            if (e.Control && e.KeyCode == Keys.D1)
            {
                tabControl1.SelectedTab = arrTabPage[0];
                arrTextBox[0].Focus();
            }
            if (e.Control && e.KeyCode == Keys.D2)
            {
                tabControl1.SelectedTab = arrTabPage[1];
                arrTextBox[1].Focus();
            }
            if (e.Control && e.KeyCode == Keys.D3)
            {
                tabControl1.SelectedTab = arrTabPage[2];
                arrTextBox[2].Focus();
            }
            if (e.Control && e.KeyCode == Keys.D4)
            {
                tabControl1.SelectedTab = arrTabPage[3];
                arrTextBox[3].Focus();
            }
            if (e.Control && e.KeyCode == Keys.D5)
            {
                tabControl1.SelectedTab = arrTabPage[4];
                arrTextBox[4].Focus();
            }
            if (e.Control && e.KeyCode == Keys.D6)
            {
                tabControl1.SelectedTab = arrTabPage[5];
                arrTextBox[5].Focus();
            }
            if (e.Control && e.KeyCode == Keys.D7)
            {
                tabControl1.SelectedTab = arrTabPage[6];
                arrTextBox[6].Focus();
            }
            if (e.Control && e.KeyCode == Keys.D8)
            {
                tabControl1.SelectedTab = arrTabPage[7];
                arrTextBox[7].Focus();
            }
            if (e.Control && e.KeyCode == Keys.D9)
            {
                tabControl1.SelectedTab = arrTabPage[8];
                arrTextBox[8].Focus();
            }
        }

        //Update font name and font size in the status line
        private void fontToolStripMenuItem_Click(object sender, EventArgs e)
        {
            intCounter = tabControl1.SelectedIndex;
            fontDialog1.ShowColor = true;
            if (fontDialog1.ShowDialog() != DialogResult.Cancel)
            {
                arrTextBox[intCounter].Font = fontDialog1.Font;
                arrTextBox[intCounter].ForeColor = fontDialog1.Color;
            }
            toolStripStatusLabelFontName.Text = "FTN: " + fontDialog1.Font.Name;
            toolStripStatusLabelFontSize.Text = "FTS: " + fontDialog1.Font.Size;
        }

        //Change the background color of a text box
        private void colorsToolStripMenuItem_Click(object sender, EventArgs e)
        {
            intCounter = tabControl1.SelectedIndex;
            if (colorDialog1.ShowDialog() != DialogResult.Cancel)
            {
                arrTextBox[intCounter].BackColor = colorDialog1.Color;
            }
        }

        //Word Wrap
        private void wordWrapToolStripMenuItem_Click(object sender, EventArgs e)
        {
            string strWordWrap;
            intCounter = tabControl1.SelectedIndex;
            if (arrTextBox[intCounter].WordWrap)
            {
                strWordWrap = "WW: F";
                arrTextBox[intCounter].WordWrap = false;
                wordWrapToolStripMenuItem.Checked = false;
            }
            else
            {
                strWordWrap = "WW: T";
                arrTextBox[intCounter].WordWrap = true;
                wordWrapToolStripMenuItem.Checked = true;
            }
            toolStripStatusLabelWordWrap.Text = strWordWrap;
        }

        //Update status line when tab changes
        private void tabControl1_Click(object sender, EventArgs e)
        {
            string strWordWrap, strFileChanged;
            intCounter = tabControl1.SelectedIndex;
            if (arrTextBox[intCounter].WordWrap)
            {
                strWordWrap = "WW: T";
            }
            else
            {
                strWordWrap = "WW: F";
            }
            if (bChanged[intCounter])
            {
                strFileChanged = "FC: T";
            }
            else
            {
                strFileChanged = "FC: F";
            }

            toolStripStatusLabelWordWrap.Text = strWordWrap;
            toolStripStatusLabelFontName.Text = "FTN: " + arrTextBox[intCounter].Font.Name;
            toolStripStatusLabelFontSize.Text = "FTS: " + arrTextBox[intCounter].Font.Size;
            toolStripStatusLabelFileName.Text = "FN: " + Path.GetFileName(strFileName[intCounter]);
            toolStripStatusLabelFileChanged.Text = strFileChanged;
        }

        //New file
        private void newToolStripMenuItem_Click(object sender, EventArgs e)
        {
            intCounter = tabControl1.SelectedIndex;
            if (bChanged[intCounter]) {
                DialogResult dialogResult = 
                    MessageBox.Show("All changes will be lost. Are you sure?", "New File", 
                    MessageBoxButtons.YesNo);
                if (dialogResult == DialogResult.No)
                {
                    return;
                }
            }
            arrTextBox[intCounter].Clear();
            bChanged[intCounter] = false;
            toolStripStatusLabelFileChanged.Text = "FC: F";
            strFileName[intCounter] = "";
            toolStripStatusLabelFileName.Text = "FN: " + strFileName[intCounter];

        }

        //Open file
        private void openToolStripMenuItem_Click(object sender, EventArgs e)
        {
            intCounter = tabControl1.SelectedIndex;
            openFileDialog1.Filter = "Text Files (.txt)|*.txt|All Files (*.*)|*.*";
            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                myOpenFile(openFileDialog1.FileName);
            }
        }

        private void myOpenFile(string strFileOpenName)
        {
                try
                {
                    System.IO.StreamReader OpenFile = new System.IO.StreamReader(strFileOpenName);
                    arrTextBox[intCounter].Text = OpenFile.ReadToEnd();
                    OpenFile.Close();
                    bChanged[intCounter] = false;
                    toolStripStatusLabelFileChanged.Text = "FC: F";
                    strFileName[intCounter] = strFileOpenName;
                    toolStripStatusLabelFileName.Text = "FN: " + 
                    Path.GetFileName(strFileName[intCounter]);

                }
                catch (Exception ex)
                {
                    MessageBox.Show("Error: Could not read file from disk. Original error: " 
                        + ex.Message);
                }
        }

        //Save file
        private void saveToolStripMenuItem_Click(object sender, EventArgs e)
        {
            intCounter = tabControl1.SelectedIndex;
            saveFileDialog1.Filter = "Text Files (.txt)|*.txt|All Files (*.*)|*.*";
            if (strFileName[intCounter] != null)
            {
                try
                {
                    System.IO.StreamWriter SaveFile = new System.IO.StreamWriter(strFileName[intCounter]);
                    SaveFile.WriteLine(arrTextBox[intCounter].Text);
                    SaveFile.Close();
                    bChanged[intCounter] = false;
                    toolStripStatusLabelFileChanged.Text = "FC: F";
                }
                catch (Exception ex)
                {
                    MessageBox.Show("Error: Could not write file to disk. Original error: " + 
                        ex.Message);
                }
            }
            else
            {
                if (saveFileDialog1.ShowDialog() == DialogResult.OK)
                {
                    try
                    {
                        System.IO.StreamWriter SaveFile = new System.IO.StreamWriter(saveFileDialog1.FileName);
                        SaveFile.WriteLine(arrTextBox[intCounter].Text);
                        SaveFile.Close();
                        strFileName[intCounter] = saveFileDialog1.FileName;
                        toolStripStatusLabelFileName.Text = "FN: " + 
                            Path.GetFileName(strFileName[intCounter]);
                        bChanged[intCounter] = false;
                        toolStripStatusLabelFileChanged.Text = "FC: F";
                    }
                    catch (Exception ex)
                    {
                        MessageBox.Show("Error: Could not write file to disk. Original error: " + 
                            ex.Message);
                    }
                }
            }
        }

        //Save As
        private void saveAsToolStripMenuItem_Click(object sender, EventArgs e)
        {
            intCounter = tabControl1.SelectedIndex;
            saveFileDialog1.Filter = "Text Files (.txt)|*.txt|All Files (*.*)|*.*";
            if (saveFileDialog1.ShowDialog() == DialogResult.OK)
            {
                try
                {
                    System.IO.StreamWriter SaveFile = new System.IO.StreamWriter(saveFileDialog1.FileName);
                    SaveFile.WriteLine(arrTextBox[intCounter].Text);
                    SaveFile.Close();
                    strFileName[intCounter] = saveFileDialog1.FileName;
                    toolStripStatusLabelFileName.Text = "FN: " + Path.GetFileName(strFileName[intCounter]);
                    bChanged[intCounter] = false;
                    toolStripStatusLabelFileChanged.Text = "FC: F";
                }
                catch (Exception ex)
                {
                    MessageBox.Show("Error: Could not write file to disk. Original error: " + 
                        ex.Message);
                }
            }
        }

        //Status bar on | off
        private void statusBarToolStripMenuItem_Click(object sender, EventArgs e)
        {
            statusStrip1.Visible = !statusStrip1.Visible;
            statusBarToolStripMenuItem.Checked = !statusBarToolStripMenuItem.Checked;
        }

        //Undo
        private void undoToolStripMenuItem_Click(object sender, EventArgs e)
        {
            intCounter = tabControl1.SelectedIndex;
            arrTextBox[intCounter].Undo();
        }

        //Select All
        private void toolStripMenuItem3_Click(object sender, EventArgs e)
        {
            intCounter = tabControl1.SelectedIndex;
            arrTextBox[intCounter].SelectAll();
        }

        //Cut
        private void cutrToolStripMenuItem_Click(object sender, EventArgs e)
        {
            intCounter = tabControl1.SelectedIndex;
            arrTextBox[intCounter].Cut();
        }

        //Copy
        private void copyToolStripMenuItem_Click(object sender, EventArgs e)
        {
            intCounter = tabControl1.SelectedIndex;
            arrTextBox[intCounter].Copy();
        }

        //paste
        private void pasteToolStripMenuItem_Click(object sender, EventArgs e)
        {
            intCounter = tabControl1.SelectedIndex;
            arrTextBox[intCounter].Paste();
        }

        //About...
        private void aboutK9padToolStripMenuItem_Click(object sender, EventArgs e)
        {
            AboutBox1 aboutBox = new AboutBox1();
            aboutBox.Show();
        }

        //Help...
        private void viewHelpToolStripMenuItem_Click(object sender, EventArgs e)
        {
            MessageBox.Show("No help for you!", "HEEEELP!!!!!");
        }

        //Go To line
        private void goToToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Form2 gotoBox = new Form2();            
            gotoBox.Show();

            int intGoToLine;
            if (Int32.TryParse(Form2.strGoToLine, out intGoToLine))
            {
                intCounter = tabControl1.SelectedIndex;
                arrTextBox[intCounter].HideSelection = false;
                try {
                    arrTextBox[intCounter].SelectionStart = 
                        arrTextBox[intCounter].GetFirstCharIndexFromLine(intGoToLine - 1);
                    arrTextBox[intCounter].SelectionLength = 
                        arrTextBox[intCounter].Lines[intGoToLine - 1].Length;
                    arrTextBox[intCounter].ScrollToCaret();
                }
                catch (Exception ex)
                {
                    MessageBox.Show("Out of range! Error: " + ex.Message, "Go To");
                }
            }
            else {
                return;
            }
        }

        //Find 
        private void findToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Form3 findBox = new Form3();
            findBox.ShowDialog();
        }

        //Find next
        private void findNextToolStripMenuItem_Click(object sender, EventArgs e)
        {
            int selStart;
            if (String.IsNullOrEmpty(Form3.strFind))
            {
                return;
            }
            if (Form3.bFindMatchCase)
            {
                try
                {
                    selStart = arrTextBox[intCounter].Text.IndexOf(Form3.strFind, 
                        arrTextBox[intCounter].SelectionStart + 1, StringComparison.Ordinal);
                }
                catch (Exception)
                {
                    selStart = -1;
                }
            }
            else
            {
                try
                {
                    selStart = arrTextBox[intCounter].Text.IndexOf(Form3.strFind, 
                        arrTextBox[intCounter].SelectionStart + 1, StringComparison.OrdinalIgnoreCase);
                }
                catch (Exception)
                {
                    selStart = -1;
                }
            }
            if (selStart == -1)
            {
                MessageBox.Show(Form3.strFind + " was not found", "Find");
                return;
            }
            arrTextBox[Form1.intCounter].Select(selStart, Form3.strFind.Length);
            arrTextBox[Form1.intCounter].ScrollToCaret();           
        }

        //Replace
        private void replaceToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Form4 replaceBox = new Form4();           
            replaceBox.Show();

        }

        //Exit program
        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            if (MessageBox.Show("Are you sure you want to close?", "Nothing will be saved...", 
                MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.No)
            {
                e.Cancel = true;
            }
        }
        
        //Exit
        private void exitToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }

        //page setup
        private void PageSetupStripMenuItem3_Click(object sender, EventArgs e)
        {
            PageSetupDialog pageSetupDialog = new PageSetupDialog();
            pageSetupDialog.PageSettings = pgSettings;
            pageSetupDialog.PrinterSettings = prtSettings;
            pageSetupDialog.AllowOrientation = true;
            pageSetupDialog.AllowMargins = true;
            pageSetupDialog.ShowDialog();
        }

        //Print menu
        private void printToolStripMenuItem_Click(object sender, EventArgs e)
        {            
            printDoc.DefaultPageSettings = pgSettings;
            PrintDialog dlg = new PrintDialog();
            dlg.Document = printDoc;
            if (dlg.ShowDialog() == DialogResult.OK)
            {
                strToPrint = arrTextBox[intCounter].Text;
                printDoc.Print();
            }
        }

        //Print Preview
        private void PrintPreviewStripMenuItem3_Click(object sender, EventArgs e)
        {
            PrintPreviewDialog dlg = new PrintPreviewDialog();            
            dlg.Document = printDoc;
            strToPrint = arrTextBox[intCounter].Text;
            dlg.ShowDialog();
        }

        //Print Document
        private void printDoc_PrintPage(Object sender, PrintPageEventArgs e)
        {
            int charactersOnPage = 0;
            int linesPerPage = 0;
              
            e.Graphics.MeasureString(strToPrint, arrTextBox[intCounter].Font,
                e.MarginBounds.Size, StringFormat.GenericTypographic,
                out charactersOnPage, out linesPerPage);
            e.Graphics.DrawString(strToPrint, arrTextBox[intCounter].Font, Brushes.Black,
                e.MarginBounds, StringFormat.GenericTypographic);
            strToPrint = strToPrint.Substring(charactersOnPage);
            e.HasMorePages = (strToPrint.Length > 0);
        }

    }
}

using System;
using System.Windows.Forms;

namespace k9pad
{
    public partial class Form2 : Form
    {
        public static string strGoToLine;
        public Form2()
        {
            InitializeComponent();           
            textBoxGoTo.Select();
            textBoxGoTo.Focus();
        }

        //Cancel
        private void btnCancel_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        //Go To when pressed enter or esc
        private void textBoxGoTo_KeyPress(object sender, KeyPressEventArgs e)
        {
            e.Handled = !char.IsDigit(e.KeyChar) && !char.IsControl(e.KeyChar);
        }

        //Execute Go To
        private void btnGoTo_Click(object sender, EventArgs e)
        {
            strGoToLine = textBoxGoTo.Text;
            this.Close();
        }

        private void textBoxGoTo_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Enter)
            {
                btnGoTo.PerformClick();
                e.SuppressKeyPress = true;
                e.Handled = true;
            }
            if (e.KeyCode == Keys.Escape)
            {
                btnCancel.PerformClick();
                e.SuppressKeyPress = true;
                e.Handled = true;
            }
        }
    }
}

using System;
using System.Windows.Forms;

namespace k9pad
{
    public partial class Form3 : Form
    {       
        public static string strFind;
        public static bool bFindMatchCase;

        public Form3()
        {
            InitializeComponent();
            bFindMatchCase = false;
        }

        //Cancel
        private void btnCancel_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        //Find
        private void btnFind_Click(object sender, EventArgs e)
        {
            int intSelStart;
            strFind = textFind.Text;
            if (bFindMatchCase)
            {
                try
                {
                    intSelStart = Form1.arrTextBox[Form1.intCounter].Text.IndexOf(strFind, StringComparison.Ordinal);
                }
                catch (Exception)
                {
                    intSelStart = -1;
                }
            }
            else
            {
                try
                {
                    intSelStart = Form1.arrTextBox[Form1.intCounter].Text.IndexOf(strFind, StringComparison.OrdinalIgnoreCase);
                }
                catch (Exception)
                {
                    intSelStart = -1;
                }
            }
            if (intSelStart == -1)
            {
                MessageBox.Show(strFind + " was not found", "Find");
                return;
            }
            Form1.arrTextBox[Form1.intCounter].Select(intSelStart, strFind.Length);
            Form1.arrTextBox[Form1.intCounter].ScrollToCaret();
            this.Close();
        }

        //Match case
        private void chkMatchCase_CheckStateChanged(object sender, EventArgs e)
        {
            bFindMatchCase = !bFindMatchCase;
        }

        private void textFind_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Enter)
            {
                btnFind.PerformClick();             
                e.SuppressKeyPress = true;
                e.Handled = true;
            }
            if (e.KeyCode == Keys.Escape)
            {
                btnCancel.PerformClick();
                e.SuppressKeyPress = true;
                e.Handled = true;
            }
        }
    }
}

using System;
using System.Text;
using System.Windows.Forms;

namespace k9pad
{
    public partial class Form4 : Form
    {
        private bool bReplaceMatchCase;
        private StringComparison scMatchCase;

        public Form4()
        {
            InitializeComponent();
            bReplaceMatchCase = false;
        }

        private void btnCancel_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        private void btnReplace_Click(object sender, EventArgs e)
        {
            if (Form1.arrTextBox[Form1.intCounter].SelectedText != "")
            {
                Form1.arrTextBox[Form1.intCounter].SelectedText = textWith.Text;
            } else
            {
                MessageBox.Show("Click Find Next first", "Find");
            }
        }

        private void btnFindNext_Click(object sender, EventArgs e)
        {
            int selStart;
            if (String.IsNullOrEmpty(textWhat.Text))
            {
                return;
            }
            if (bReplaceMatchCase)
            {
                selStart = Form1.arrTextBox[Form1.intCounter].Text.IndexOf(textWhat.Text, Form1.arrTextBox[Form1.intCounter].SelectionStart + 1, StringComparison.Ordinal);
            }
            else
            {
                selStart = Form1.arrTextBox[Form1.intCounter].Text.IndexOf(textWhat.Text, Form1.arrTextBox[Form1.intCounter].SelectionStart + 1, StringComparison.OrdinalIgnoreCase);

            }
            if (selStart == -1)
            {
                MessageBox.Show(textWhat.Text + " was not found", "Replace");
                return;
            }
            Form1.arrTextBox[Form1.intCounter].Select(selStart, textWhat.Text.Length);
            Form1.arrTextBox[Form1.intCounter].HideSelection = false;
            Form1.arrTextBox[Form1.intCounter].ScrollToCaret();            
        }

        private string ReplaceString(string strInputString, string strOldValue, string strNewValue, StringComparison scComparison)
        {
            StringBuilder sbTempString = new StringBuilder();

            int previousIndex = 0;
            int index = strInputString.IndexOf(strOldValue, scComparison);
            while (index != -1)
            {
                sbTempString.Append(strInputString.Substring(previousIndex, index - previousIndex));
                sbTempString.Append(strNewValue);
                index += strOldValue.Length;

                previousIndex = index;
                index = strInputString.IndexOf(strOldValue, index, scComparison);
            }
            sbTempString.Append(strInputString.Substring(previousIndex));

            return sbTempString.ToString();
        }

        private void chkMatchCase_CheckStateChanged(object sender, EventArgs e)
        {
            bReplaceMatchCase = !bReplaceMatchCase;
            if (bReplaceMatchCase)
            {
                scMatchCase = StringComparison.Ordinal;
            }
            else
            {
                scMatchCase = StringComparison.OrdinalIgnoreCase;
            }
        }

        private void btnReplaceAll_Click(object sender, EventArgs e)
        {
            Form1.arrTextBox[Form1.intCounter].Text = ReplaceString(Form1.arrTextBox[Form1.intCounter].Text, textWhat.Text.Trim(), textWith.Text.Trim(), scMatchCase);
        }

        private void textWhat_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Enter)
            {
                btnFindNext.PerformClick();
                e.SuppressKeyPress = true;
                e.Handled = true;
            }
            if (e.KeyCode == Keys.Escape)
            {
                btnCancel.PerformClick();
                e.SuppressKeyPress = true;
                e.Handled = true;
            }
        }
    }
}