Array of "bytes"

This is a discussion on Array of "bytes" within the C Programming forums, part of the General Programming Boards category; Hi all, I would like to declare an array of "bytes" like that: Code: <SOMETHING> pool[10000]; For example: Code: char ...

  1. #1
    Beginning game programmer Petike's Avatar
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    Question 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.
    Petike

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    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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    Last edited by matsp; 10-08-2008 at 03:46 PM.

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    Beginning game programmer Petike's Avatar
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    Thanks.
    Petike

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    Banned master5001's Avatar
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    As far as I am aware, however the size of a byte is not necessarily a constant.

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    Quote Originally Posted by master5001 View Post
    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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    Banned master5001's Avatar
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    So you did. Good show.

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    C++まいる!Cをこわせ! Elysia's Avatar
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    Typically, raw data or buffers use unsigned char.
    I believe BYTE is defined as unsigned char in the Windows headers...
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

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    Quote Originally Posted by Elysia View Post
    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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    If you want to talk about where the designers of C went wrong... Signed and unsigned should never have been made attributes of the variables. Because this leads to issues when unsigned and signed are mixed. Instead, just the size should have been sufficient. Then introduce signed vs. unsigned operators: plus, minus, times, etc. Some languages do it that way. After all, it's only during math that it matters. Not while it's stored.

    Here is another proof why the current system is foolish. Format strings in printf() and the like need to specify the signedness once again... because the ephemeral variable attribute is not recognizable any other way.

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