Thread: Basic doubt in C structure

Hi all,

I was navigating inside linux kernel code and inside that one i have seen few structures which are very strange (for me). The structure is of the following form

Code:

struct dummy {
     int a:1;
     unsigned long b:5;
};

In the above structure does anyone explain me what is the number after the : will do.

Thanks in advance
-BalaC-

It's called a bitfield.

a is a bitfield (like an int or char, but with one bit). b too, but with five bits. "a = 2" will probably give 0, since the upper bits are chopped off.