?
Solved

extract a byte out of an integer

Posted on 2008-06-11
6
Medium Priority
?
1,324 Views
Last Modified: 2010-04-21
Hi,

How do I extract a byte out of an integer. For example, I like to get the first byte of a 4-byte integer.
Thanks
0
Comment
Question by:mycuti08
  • 4
  • 2
6 Comments
 
LVL 40

Expert Comment

by:evilrix
ID: 21759102
>> For example, I like to get the first byte of a 4-byte integer.
Something like below...
int main()
{
	unsigned int dw = 0xFFEEDDCC;
	unsigned char byte0 = dw & 0xFF;
	unsigned char byte1 = (dw >> 8) & 0xFF;
	unsigned char byte2 = (dw >> 16)  & 0xFF;
	unsigned char byte3 = (dw >> 24) & 0xFF;
}

Open in new window

0
 
LVL 40

Expert Comment

by:evilrix
ID: 21759137
Re: { http:#21759102 }

For each byte we need to use bitwise and (&) to mask in only 1 byte, we then just bit-shift 0, 8, 16 or 32 bits to the right so we can mask in byte 0, 1, 2 or 3 and exclude the rest. The bit-shift operators don't behave as you'd expect with signed types (they take into account the sign of the type and maintain it during shifting) so when doing bitwise arithmetic it is always best to use unsigned types.
0
 
LVL 40

Accepted Solution

by:
evilrix earned 800 total points
ID: 21759153
You might find this tutorial helpful: http://www.cprogramming.com/tutorial/bitwise_operators.html
0
Concerto's Cloud Advisory Services

Want to avoid the missteps to gaining all the benefits of the cloud? Learn more about the different assessment options from our Cloud Advisory team.

 

Author Closing Comment

by:mycuti08
ID: 31466106
Thanks evilrix. It worked great
0
 
LVL 40

Expert Comment

by:evilrix
ID: 21759180
>> Thanks evilrix. It worked great
Did you understand how/why it worked?
0
 

Author Comment

by:mycuti08
ID: 21759486
yes I did.
Thanks evilrix
0

Featured Post

Upgrade your Question Security!

Add Premium security features to your question to ensure its privacy or anonymity. Learn more about your ability to control Question Security today.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Article by: SunnyDark
This article's goal is to present you with an easy to use XML wrapper for C++ and also present some interesting techniques that you might use with MS C++. The reason I built this class is to ease the pain of using XML files with C++, since there is…
IntroductionThis article is the second in a three part article series on the Visual Studio 2008 Debugger.  It provides tips in setting and using breakpoints. If not familiar with this debugger, you can find a basic introduction in the EE article loc…
The goal of this video is to provide viewers with basic examples to understand and use switch statements in the C programming language.
The viewer will learn additional member functions of the vector class. Specifically, the capacity and swap member functions will be introduced.
Suggested Courses

750 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question