A simple question

OpenGL OpenGL: Basic Coding
1

Hello, I’ve a simple question. I’m going through some code related with writing a bmp image file.

In the following code, what does ‘filesize>>8’ imply? How is it used in a bmp file?

bmpfileheader[ 2] = (unsigned char)(filesize );
bmpfileheader[ 3] = (unsigned char)(filesize>> 8);
bmpfileheader[ 4] = (unsigned char)(filesize>>16);
bmpfileheader[ 5] = (unsigned char)(filesize>>24);

Thanks.

2

I understand, this is just offset in the bmp file header.

3

The file size in the image is little endian. This code stores the integer as little endian irregardless of the
machines actual endianness.

The code assumes that a character has 8 bits. The first line extracts the first byte of the integer, the
second line the next higher byte (shifting it to the right by 8 bits and cutting the rest off), the third line
the next higher bytes (shifting it right by 16, cutting the rest of) and the last line extracts the highest
byte.