Try this
private void button1_Click(object sender, EventArgs e)
{
dlgFileOpen.Filter = "Bitmap Files(*.bmp)|*.bmp|Other Image Files(*.jpg)|*.jpg|" +
"Text Files(*.txt) | *.txt|All Files(*.*)|*.*";
if (dlgFileOpen.ShowDialog() == DialogResult.OK)
{
txtSelectedFile.Text = dlgFileOpen.FileName;
string ext = Path.GetExtension(dlgFileOpen.FileName);
if (ext.ToLower() == ".bmp" || ext.ToLower() == ".jpg")
{
txtFileContent.Visible = false;
pict.Visible = true;
pict.SizeMode = PictureBoxSizeMode.StretchImage;
pict.Load(dlgFileOpen.FileName);
}
else
{
txtFileContent.Visible = true;
pict.Visible = false;
FileStream fstream = new FileStream(dlgFileOpen.FileName, FileMode.Open);
StreamReader reader = new StreamReader(fstream);
while (reader.EndOfStream != true)
{
txtFileContent.AppendText(reader.ReadLine());
txtFileContent.AppendText(Environment.NewLine);
}
reader.Close();
}
}
}