Array of char using unique_ptr in this specific case

Question

I am currently working on a little server using sockets in C++.

I have a function which sends string:

void SocketServer::SendData(int id_client, const std::string &str)
{
  int size = str.size();
  send(id_client, &size, 4, 0);
  send(id_client, str.c_str(), str.size(), 0);
}

First, I send 4 bytes which corresponds to the length of the string I want to send.

Then, I have a function which receives the string:

int SocketServer::ReceiveData(int id_client)
{
  char  buffer[1024]; // <<< this line, bad idea, I want to use unique_ptr
  int size = 0;
  int ret = 0;

  ret = recv(id_client, &size, 4, 0);  //<<< Now I know the length of the string I will get

  if (ret >= 0)
  {
    ret = recv(id_client, buffer, size, 0);
    if (ret >= 0)
    {
      buffer[ret] = '\0';
      std::cout << "Received: " << buffer << std::endl;
    }
  }
  return (ret);
}

I don't want to use a fixed buffer and I would like to use the unique_ptr (because it is a good way to respect the RAII)

How could I do that ?

Thank you very much

void · Accepted Answer · 2017-04-27 19:38:18Z

6

You could just use std::string instead:

std::string buffer;
int size = 0;                                                                                          
int ret = 0;                                                                                           

ret = recv(id_client, &size, 4, 0);
buffer.resize(size);

//later..
recv(id_client, &buffer[0], size, 0);

buffer will now contain the received data and the correct size. It will also be destroyed for you because of RAII.

edited Apr 27, 2017 at 19:38

void

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answered Apr 27, 2017 at 19:27

Hatted Rooster

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6 Comments

void Over a year ago

Hello, thank you for your answer, it works like a charm! I didn't know that std::string was also considered as char*, thank you!

void Over a year ago

Btw you were too fast for stackoverflow, I must wait 5 minutes to approve your answer, thank!

zett42 Over a year ago

@void &string[0] is only guaranteed to work since C++11 standard. See also this answer.

Hatted Rooster Over a year ago

@zett42 And OP asked about a solution with unique_ptr, which is C++11 minimally as well.

zett42 Over a year ago

Fair enough. I have suggested adding the appropriate tag.

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