Thread: Array of "bytes"

Hi all,
I would like to declare an array of "bytes" like that:

Code:

<SOMETHING> pool[10000];

For example:

Code:

char pool[10000];

But I am not sure if "sizeof(char)" always equals "1" on every machine and every operating system.
If it is "not" equal, then how could I declare an array which all elements equal "1 byte" (8 bits)?

Thanks.

The C standard says that sizeof(char) is ALWAYS 1 (don't ask me to quote the exact paragraph). However, if the machine uses a char that is 8 bits or something else is a completely different matter (most have 8-bit char, but it's not set in stone) - I don't KNOW of any machine that doesn't, but I have read about such things.

Also, bear in mind that every time you NEED something to be a particular (minimum or maximum) size, it's best to make it a typdef. You may for example do:

Code:

typedef char BYTE;

BYTE buffer[...];

That way, you can change the defintion of BYTE to something else on machines where something else is "better", without having to search through the entire source of your application/OS/etc to find where "char" is used as a BYTE and where "char" is used as a character.

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Mats

Thanks.

Originally Posted by master5001

As far as I am aware, however the size of a byte is not necessarily a constant.

Correct, and I also said in my post that a char may not always be 8 bits.
http://en.wikipedia.org/wiki/Byte

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Mats

Typically, raw data or buffers use unsigned char.
I believe BYTE is defined as unsigned char in the Windows headers...

Originally Posted by Elysia

Typically, raw data or buffers use unsigned char.
I believe BYTE is defined as unsigned char in the Windows headers...

a "BYTE" is not signed or unsigned - Windows uses BYTE, WORD, DWORD etc as signed values, but that is because those types originate from the MS Macro Assembler - but they are not signed or unsigned in assembler - that choice is made by choosing the right condition code for Jcc and SETcc instructins - if you choose the signed version, then the number is signed, and if you choose the unsigned version, then it's unsigned.

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Mats