i`m comfused please help

hello there everybody
i`m new to game programming and directx please can anyone tell what do this sentence mean ?

int index = i * lockRect.Pitch / 4 + j;

imageData[index] = 0xffff0000;

what i cant understand why did i multiplyed lockedrect.pitch with i and then divide it by 4+j ?

We're going to need to see more than those two lines. Post us the full program / function.
EDIT: Oh and code tags plskkkthxbai

Maybe, you should learn the English language before you move onto C++!

What are you trying to accomplish with that code? It does nothing from what I can see.

int index = i * lockRect.Pitch / 4 + j;

imageData[index] = 0xffff0000;

The divide by 4 is to convert bytes into DWORDs or UINTs.. Pitch is expressed in bytes. 1 UINT or DWORD is 4 bytes.
You should group your operations with parentheses to make for easier reading of the code.

Code:

int index = i * (lockRect.Pitch >> 2) + j;

imageData[index] = 0xffff0000;

Shift right is same as dividing by 2^shift.
Shift left is same as multiplying by 2^shift.

I would say your code worked as planned because multiplication is first, then division, then addition, etc, etc. But it's always a good idea to group the operations for clarity and to ensure the operations are being done in the correct order.

thanks everybody for the replays
bubba thanks for the explanation

Ah, so we didn't need it all. Rather, Bubba didn't. Good ol' Bubs

I'm here for ya's all.

So don't go posting stuff I don't know anything about and we'll get along just fine. The stuff I don't know is pretty much everything John Carmack knows....so no John Carmack threads.

What are Mega-Textures(tm)?

Those crazy things he talked about for terrain and such which I still don't quite understand how they work or would work. I read the article but it was quite sparse and didn't make sense.
I think it means generating a huge texture and then using it on a surface. The texture is so big that you would not get any repeating or tiling.