Re: Bitfields

[HIToC <hitoc_mail@yahoo.it>]

On Wednesday 01 December 2004 05:25, Jagadeesh Bhaskar P wrote:
> Hi all,
> 	What is a bitfield? How is it used in C??
>
> TIA


It is possible to use several of bit variables like fields within a struct.
You have to indicate first the name of the field, then the number of bits
that the field occupies. Also you have to put double points ":" between
the filed's name and its bit-size.
For example, you want to save the current date; you can define a
struct Date (YYYY/MM/DD) like this

struct Date {                              // Date format: YYYY/MM/DD
	unsigned	year    : 7;         // 0-127 (2000-2127)   [7 bits size]
	unsigned	month  : 4;		// 1-12                       [4 bits size]
	unsigned	day      : 5;        // 1-31                       [5 bits size]
};

In this case we have the complete date in a 16 bit variable (7+4+5=16 bit)!

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