Can we access pointers in C#?

Question

I just want to know where we can use pointers in C#.

we can use pointers in C++ but i have no idea where we can use them in C#.

I also want to know if there is any pointer used in unmanaged code.

You can access pointers in an `unsafe` context. Otherwise you don't: the language obscures it. — Jeroen Vannevel, Dec 19 '13 at 02:23
You'll rarely (if ever) use pointers in C#. See http://stackoverflow.com/questions/5171781/when-to-use-pointers-in-c-net — mason, Dec 19 '13 at 02:26
Why do you _want_ to access pointers? What are you trying to achieve that you can't without pointers? — John Saunders, Dec 19 '13 at 02:31

score 3 · Answer 1 · answered Dec 19 '13 at 03:34

Yes, you can use pointers. See unsafe keyword.

An example of a pratical use: convert image to grayscale

public static Bitmap MakeGrayscale2(Bitmap original)
{
   unsafe
   {
      //create an empty bitmap the same size as original
      Bitmap newBitmap = new Bitmap(original.Width, original.Height);

      //lock the original bitmap in memory
      BitmapData originalData = original.LockBits(
         new Rectangle(0, 0, original.Width, original.Height),
         ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);

      //lock the new bitmap in memory
      BitmapData newData = newBitmap.LockBits(
         new Rectangle(0, 0, original.Width, original.Height), 
         ImageLockMode.WriteOnly, PixelFormat.Format24bppRgb);

      //set the number of bytes per pixel
      int pixelSize = 3;

      for (int y = 0; y < original.Height; y++)
      {
         //get the data from the original image
         byte* oRow = (byte*)originalData.Scan0 + (y * originalData.Stride);

         //get the data from the new image
         byte* nRow = (byte*)newData.Scan0 + (y * newData.Stride);

         for (int x = 0; x < original.Width; x++)
         {
            //create the grayscale version
            byte grayScale = 
               (byte)((oRow[x * pixelSize] * .11) + //B
               (oRow[x * pixelSize + 1] * .59) +  //G
               (oRow[x * pixelSize + 2] * .3)); //R

            //set the new image's pixel to the grayscale version
            nRow[x * pixelSize] = grayScale; //B
            nRow[x * pixelSize + 1] = grayScale; //G
            nRow[x * pixelSize + 2] = grayScale; //R
         }
      }

      //unlock the bitmaps
      newBitmap.UnlockBits(newData);
      original.UnlockBits(originalData);

      return newBitmap;
   }
}

As seen here.

Thanks , Very nice dicription – Saket Kumar Dec 20 '13 at 17:33 — Saket Kumar, Dec 20 '13 at 17:33

Can we access pointers in C#?

1 Answers1