Thread: Help with a bit manipulation program.

1. Don't bump your own threads.
2. No, we won't do your homework for you.
3. Educating is a two step process. Your teacher may "suck" at teaching, but apparently you haven't done your part to learn anything.

Show us your start, and then ask specific questions.

I'll start by telling you that

Code:

unsigned char MyUnsigned8BitVariable

will get you your 8 bit number.

Code:

unsigned char

is exactly one byte. I hope you know how to do input and output. Other than that, I hope you can figure out how to write a function to convert decimal to binary. If you can't figure it out then show me the code that you have and I'll actually try to help you rather than complaining that you're trying to get help on your assignment.

You asked for a starting point and I gave you one. Put your code up so that I can help you.

>will get you your 8 bit number
It will? Oh, I see. Clearly it's an 8-bit number because you called it "MyUnsigned8BitVariable" and C compilers are smart enough to know that you want 8 bits and give you exactly 8 bits.

Now, if you said "will get you your 8 bit number on most modern machines", I would have passed you by with a smile because you were clever enough to cover your butt from nitpickers. char is not required to be 8 bits. Why do you think CHAR_BIT exists?

That wasn't a response that I had planned for.

In 8 bit game programming, you always use and unsigned char to represent an 8 bit pixel. There may be an exception on a small amount of computers, but using an unsigned char is still very reliable.

I know that more than likely, an unsigned char will be 8 bits on his computer and since he is having trouble with this assignment, I didn't want to worry him with the fact that there is a very small chance that this might be false. If you are concerned with the number of bytes an unsigned char is on your computer, this program will tell you:

Code:

#include <stdio.h>

int main()
{
	printf("The size of an unsigned char on this machine is %d byte(s).\n",
		   sizeof(unsigned char));
	return 0;
}

If this tells you that an unsigned char is more than 1 byte on your computer then I am deeply sorry for not considering that possibility. IF IT IS 1 BYTE THEN DON'T CRY LIKE A LITTLE BABY EVERY TIME YOU SEE A TINY INSIGNIFICANT ERROR. TRY HELPING PEOPLE RATHER THAN COMPLAINING ABOUT PEOPLE WHO ARE TRYING TO HELP.

I see you have 7,714 posts right now. I hope that at least one of them actually helped someone.

Actually, sizeof(char) will always be 1 so that program wouldn't give you anything useful.

Not on machines where a char is 2 bytes.

I also forgot to mention that if you are like Prelude and are worried that a char is actually 2 bytes, you can always remove any extra bits by simply doing this:

Code:

char character;
// change all the extra bits to zero
character = character & 255;

Prelude didn't mention that. Maybe she didn't know or was just to busy complaining that she forgot to mention.

Originally Posted by Brad0407

Not on machines where a char is 2 bytes.

It is now you passing disinformation; you could stand to learn a little more before tyring not to confuse others.

Originally Posted by Brad0407

Not on machines where a char is 2 bytes.

I also forgot to mention that if you are like Prelude and are worried that a char is actually 2 bytes, you can always remove any extra bits by simply doing this:

Code:

char character;
// change all the extra bits to zero
character = character & 255;

Prelude didn't mention that. Maybe she didn't know or was just to busy complaining that she forgot to mention.

Stop crying about your imagined hurt feelings and pay attention. We, the people who know what the hell they're talking about, tend to state facts pulled from the standard. The standard is what defines the C language.

You come in and say "A byte is 8 bits!", as a flat out truth. Well, I hate to tell you this* but if you learned anything from grade school tests it's that "If any part of a statement is false, the whole thing is false."

As such, your statement is false. Bytes are not 8 bits. They're CHAR_BIT bits. You see, the C language doesn't care where it's compiled. It does know however, that the number of bits in a byte is CHAR_BIT. So while what you do on your machine may be correct in some cases, when I say "A byte is CHAR_BIT bits in size!", I am correct in all cases.

The point is, if you're going to try and teach people, do it correctly. So stop crying like a wuss and be surprised that you with your supposed "mad skillz" have actually learned something today.


Quzah.
*Actually, I don't hate it, but it makes for a better sentence than: "You're such a ........ing idiot."

When the **** is a byte not 8 bits?

A bit is a bit
A nibble is 4 bits
A byte is 8 bits

Did they not teach you that when you learned the standard?
If the standard of a byte is not 8 bits then the guy that is writing his ****ing program is going to have a **** of a time trying to write a program where 8 bits is 1 ****ing byte. And yes I have run this program on a computer with 2 bytes for characters and the result came back as 2 bytes.

With that anger out, I'd like to say that I figured out how to work out the bottom line of signature, quzah, but I don't know how to display it. lol.

I still think that using an unsigned char is the best way to go and I would do it myself.

To think that all this started because I was thinking of helping torqueywrench and not about pointing out every single flaw. I wasn't "covering my butt from nitpickers".

I did learn something today, quzah, that did surprise me. You know what it is? The people that are smart enough to help nitpick the people doing their best to help. I also learned that these forums are started with good intentions but end up being ruined by people that have no social life because all they do is insult others.

Originally Posted by Brad0407

When the **** is a byte not 8 bits?

From http://en.wikipedia.org/wiki/Byte:

The word "byte" has several meanings, all closely related:

1. A contiguous sequence of a fixed number of bits. On modern computers, an eight-bit byte or octet is by far the most common. This was not always the case. Certain older models have used six-, seven-, or nine-bit bytes - for instance on the 36-bit architecture of the PDP-10. Another example of a non eight-bit sequence is the 12-bit slab of the NCR-315. A byte is always atomic on the system, meaning that it is the smallest addressable unit. An eight-bit byte can hold 256 possible values (28 = 256) -- enough to store an unsigned integer ranging from 0 to 255, a signed integer from -128 to 127, or a character of a seven-bit (such as ASCII) or eight-bit character encoding.

A simple google search would have given you the answer.

And I'd like to know where you came across this computer that returned 2 for sizeof(char) and the details of it. I think your memory is mistaken.