CODEWITHSUNDEEP
c++vector
Marshel Abraham
Marshel Abraham

Reputation: 97

std::copy from memory buffer to vector

I am trying to copy binary data from a mem buffer to a vector.

Please let me know what is wrong with the folloowing attempts

each time I am getting vector size as 0

int AhaConnectAPI::unpackDataArray(uint8_t* src, vector<uint64_t> dest, uint32_t destvectorSize, int offset)
{

    cout<<"\nstd::copy";
    std::copy(src + offset, src + offset + sizeof(uint64_t) * length, back_inserter(dest));
    return length * 8;
}

or

int AhaConnectAPI::unpackDataArray(uint8_t* src, vector<uint64_t> dest, uint32_t destvectorSize, int offset)
{

    uint64_t element;

    for(unsigned int i = 0 ; i<destvectorSize; i++)
    {
         offset = unpackData(src, element, offset);
         dest.push_back(element);
    }

    return dest.size() * sizeof(uint64_t);

}

Upvotes: 2

Views: 1425

Answers (2)

Ajay
Ajay

Reputation: 18421

Try this:

int AhaConnectAPI::unpackDataArray(uint8_t* src, vector<uint64_t>& dest, 
                                   uint32_t destvectorSize, int offset)

You need to pass vector by reference (note the &).

Upvotes: 1

Paul Evans
Paul Evans

Reputation: 27577

In your first unpackDataArray(): your src is of type uint8_t* but you use sizeof(uint64_t) in std::copy and for dest, and offset is an int. Try something like:

std::copy(static_cast<uint64_t*>(src) +
              static_cast<uint64_t>(offset),
          static_cast<uint64_t*>(src) +
              static_cast<uint64_t>(offset) + sizeof(uint64_t) * length,
          back_inserter(dest));

offset may need further adjustment. Also length appears out of nowhere.

Upvotes: 3

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