C#

static class ExtMethod
    {
        public static StringBuilder SubString(this StringBuilder sr1, int startPos, int length)
        {
            StringBuilder randomString = new StringBuilder();
            char[] charArray = new char[length];
            sr1.CopyTo(startPos, charArray, 0, length);
            randomString.Append(charArray);
            return randomString;
        }
    }

// We know how long the output needs to be, so preallocate capacity
StringBuilder output = new StringBuilder(length);
 
for ( int i = 0; i < length; ++i )
{
   output.Append( sr1.Chars[i] );
}
 
return output;

if (this.SelectionStart < 4)
                {                    
                    //string text = this.Text;
                    //this.strYear = text.Substring(0, 4);
                    //int num = int.Parse(this.strYear) + 1;
                    //this.strYear = num.ToString();
                    //this.strDate = string.Format("{0}/{1}/{2}", this.strYear, this.strMonth, this.strDay);
                    //this.Text = this.strDate;
                    e.Handled = true;
                }

public static bool Extract(Bitmap b)
{
  BitmapData bmData = b.LockBits(new Rectangle(0,0, b.Width, b.Height),
    ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
  int stride = bmData.Stride;
  IntPtr scan0 = bmData.Scan0;
  unsafe
  {
    byte *p = (byte*)(void*)scan0;
    //... Extract the image here
    
  }
}

Krish Agn wrote:

But I used _paint event in my class to create the control, which is not possible to create the same in class library project.

loke6258038 wrote:

to detect when a client on purpose power down his PC without closing the connection