how to convert vector<vector<unsigned char> > to vector<unsigned char*> ?
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Thread: how to convert vector<vector<unsigned char> > to vector<unsigned char*> ?

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    how to convert vector<vector<unsigned char> > to vector<unsigned char*> ?

    Hello,

    I have a vector<vector<unsigned char> > and I want to convert it to a vector<unsigned char*>. Can anyone provide sample code of how this is done?

    Thanks!
    Charles
    Last edited by clow; August 19th, 2014 at 01:20 PM.

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    Re: how to convert vector<vector<unsigned char> > to vector<unsigned char*> ?

    Victor Nijegorodov

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    Re: how to convert vector<vector<unsigned char> > to vector<unsigned char*> ?

    Quote Originally Posted by clow View Post
    Hello,

    I have a vector<vector<unsigned char> > and I want to convert it to a vector<unsigned char*>. Can anyone provide sample code of how this is done?

    Thanks!
    Charles
    The big question here is not how you convert from one container type to another, but rather, how will you be converting the elements themselves, eg: vector<unsigned char> to unsigned char*.

    There are two issues:
    1. vector<unsigned char> has length information. unsigned char* does not. How will you deal with this. Are we to just assume that your unsigned char sequences are null terminated? Or that someone else knows how long those sequences are?
    2. vector<unsigned char> has ownership of its elements. unsigned char* does not. Who will be responsible for storing the elements, and for cleaning them up?

    In any case, as VictorN replied, extracting an unsigned char* from vector<unisgned char> is done via the function "data". From there, a simple for loop can convert all elements.
    Is your question related to IO?
    Read this C++ FAQ LITE article at parashift by Marshall Cline. In particular points 1-6.
    It will explain how to correctly deal with IO, how to validate input, and why you shouldn't count on "while(!in.eof())". And it always makes for excellent reading.

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