I'm getting error: expected identifier or '(' with the code below

Question

    BITMAPFILEHEADER.bfSize = BITMAPFILEHEADER.bfSize * n;
    BITMAPINFOHEADER.biWidth = BITMAPINFOHEADER.biWidth * n;
    BITMAPINFOHEADER.biHeight = 0xffffffff - ((0xffffffff - BITMAPINFOHEADER.biHeight) * n);
    BITMAPINFOHEADER.biSizeImage = BITMAPINFOHEADER.biSizeImage * n;

Answer 1

To refer to hexadecimals on C code you prefix the number with 0x

Change your ffffffff with 0xffffffff

UPDATE

BITMAPFILEHEADER and BITMAPINFOHEADER are variable types not variables themselves.

You can declare one variable of each type like this:

BITMAPFILEHEADER bf;
BITMAPINFOHEADER bi;

and then refer to the variables in the structs like this :

bf.bfSize = bf.bfSize * n;
bi.biWidth = bi.biWidth * n;
bi.biHeight = 0xffffffff - ((0xffffffff - bi.biHeight) * n);
bi.biSizeImage = bi.biSizeImage * n;