problem with fout.write: cannot write 0x0A (10 dec)

This is a discussion on problem with fout.write: cannot write 0x0A (10 dec) within the C++ Programming forums, part of the General Programming Boards category; hello, i m trying to write the content of a pointer to a file: unsigned char* ds=(unsigned char*)malloc(sizeof(unsigned char)*width*height); ofstream ...

  1. #1
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    Unhappy problem with fout.write: cannot write 0x0A (10 dec)

    hello, i m trying to write the content of a pointer to a file:


    unsigned char* ds=(unsigned char*)malloc(sizeof(unsigned char)*width*height);

    ofstream fout(outname);

    fout.write(reinterpret_cast<const char*>(&(*ds)), width*height);


    (i tried sizeof(*ds) instead of width*height but it does not work)


    all it does is return a file slightly BIGGER than width*heigth, because of the following issue: the char 0x0A cannot be written, it is replaced by 0x0D0A (that s right, 2 chars for the price of 1)

    can anyone help me on this, please? (no need to mention that i m new to MSVC++ .NET ...)

    thanks a lot!
    -yves-

  2. #2
    Registered User hk_mp5kpdw's Avatar
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    Open the file in binary mode to not have the 0x0A automatically converted to 0x0D,0x0A:

    Code:
    ofstream fout(outname,ios::binary|ios::out);
    "Owners of dogs will have noticed that, if you provide them with food and water and shelter and affection, they will think you are god. Whereas owners of cats are compelled to realize that, if you provide them with food and water and shelter and affection, they draw the conclusion that they are gods."
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  3. #3
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    open the output file as binary

    ofstream fout(outname, ios_base::binary);
    Nana C++ Library is a GUI framework that designed to be C++ style, cross-platform and easy-to-use.

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    thanks a lot!

    works like a charm now!!


  5. #5
    Cat without Hat CornedBee's Avatar
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    Note that sizeof(unsigned char) is guaranteed to be 1 by the standard.
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
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  6. #6
    Sweet
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    Oh and why not use new and delete instead of malloc
    Woop?

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    malloc vs new ?

    what would be the advantages of using new instead of malloc?

    i m having some memory leaks problems, could that be due to malloc - is new better in terms of memory management?

    -yves-

  8. #8
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    You are writing in C++, you should use new/delete - malloc/free does not call constructors or destructors, so you will eventually need new/delete in your C++ code. It makes no sense to use both. There are some advanced reasons to use malloc in a C++ program, but if you don't know what they are you shouldn't be using them.

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