BYTE, char data corruption

This is a discussion on BYTE, char data corruption within the C++ Programming forums, part of the General Programming Boards category; Originally Posted by Denethor2000 error C2440: 'initializing' : cannot convert from 'unsigned char [300]' to 'unsigned char' What's _Buffer? According ...

  1. #16
    Frequently Quite Prolix dwks's Avatar
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    Quote Originally Posted by Denethor2000
    error C2440: 'initializing' : cannot convert from 'unsigned char [300]' to 'unsigned char'
    What's _Buffer? According to the error, it's an 'unsigned char'.
    dwk

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  2. #17
    Super Moderator Harbinger's Avatar
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    > input Line = { GetCurrentProcessId(), Address, Length, _Buffer };
    You can't assign arrays - use memcpy()

    Having BYTE *bytes; in your struct would work, but that wouldn't be making a copy of the buffer.

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    Quote Originally Posted by dwks
    What's _Buffer? According to the error, it's an 'unsigned char'.
    Yeah, I edited that in a minute later, sorry about that.

    It's a BYTE array.
    Code:
    BYTE _Buffer[300];

  4. #19
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    Code:
    input Line = { GetCurrentProcessId(), Address, Length, _Buffer };
    What the hell is the above? what are those curly-braces doing there? First calls GetCurrentProcessID() and assigns the return value to Line (which is wrong because Input is not a DWORD). but what's the purpose of Address, Length, and _Buffer in that line?
    Last edited by Ancient Dragon; 11-12-2005 at 04:42 PM.

  5. #20
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    Quote Originally Posted by Ancient Dragon
    Code:
    input Line = { GetCurrentProcessId(), Address, Length, _Buffer };
    What the hell is the above? what are those curly-braces doing there? First calls GetCurrentProcessID() and assigns the return value to Line (which is probably wrong if Input is not a DWORD). but what's the purpose of Address, Length, and _Buffer in that line?
    It's a struct. Which I included in the same post.

    It gets passed to a driver with DeviceIoControl. Which has nothing to do with my problem.

  6. #21
    Frequently Quite Prolix dwks's Avatar
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    Probably to initialize the remaining members of the structure.
    Code:
    struct s {
        int x;
        float f;
    };
    
    s one;
    s two = {1};
    s three = {1, 2.0};
    [edit]You beat me to it.[/edit]
    dwk

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  7. #22
    Frequently Quite Prolix dwks's Avatar
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    Which has nothing to do with my problem.
    It might, depending on what _Buffer is. It's [300], right?
    dwk

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  8. #23
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    Quote Originally Posted by Denethor2000
    It's a struct. Which I included in the same post..
    Yes, I reread your previous post and found that out. You can't assign members of a struct like that -- each member requires its own assign statement.
    Code:
    Line.processid = GetProcessID();
    Line.address = Address;
    Line.bytestowrite = Length;
    // The next line may not work if sizeof(Line.bytes) > siezof(_Buffer)
    memcpy(Line.bytes,_Buffer,sizeof(Line.bytes));

  9. #24
    Frequently Quite Prolix dwks's Avatar
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    You can too assign a struct like that. How about you re-read my post:

    Quote Originally Posted by dwks
    Code:
    struct s {
        int x;
        float f;
    };
    
    s one;
    s two = {1};
    s three = {1, 2.0};
    dwk

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  10. #25
    Frequently Quite Prolix dwks's Avatar
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    And what's siezof?
    dwk

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  11. #26
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    Quote Originally Posted by dwks
    You can too assign a struct like that. How about you re-read my post:
    That obscure trick won't work with his struct because it contains character arrays which cannot be copied like that.

  12. #27
    Frequently Quite Prolix dwks's Avatar
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    That obscure trick
    I use it all the time.

    won't work with his struct because it contains character arrays
    Yes, you're right. (It does work for char*, not for char[].) But
    but what's the purpose of Address, Length, and _Buffer in that line?
    Address and Length are valid.
    dwk

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  13. #28
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    Quote Originally Posted by dwks
    I use it all the time.
    You are one of a very select few who do. I've never see that before in over 20 years.


    Quote Originally Posted by dwks
    Yes, you're right. (It does work for char*, not for char[].)
    well, it really does not work for char* either -- unless all you want copied is the address and not the object to which it points.

  14. #29
    Frequently Quite Prolix dwks's Avatar
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    You are one of a very select few who do. I've never see that before in over 20 years.
    What? Really? That's amazing.

    well, it really does work for char* either -- unless all you want copied is the address and not the object to which it points.
    It does work? Oh, you mean doesn't. It does work, because all I want copied is the address.
    dwk

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  15. #30
    & the hat of GPL slaying Thantos's Avatar
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    technically you aren't doing assignment. You are doing initalization.

    Denethor2000 instead of rationing out your limitations to us how about you give us all the info in the beginning?

    A BYTE is nothing more then a fancy unsigned char.

    Changing both types to char[300] is accepted, but "corrupts" it.
    how does it corrupt it?

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