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C++ source code snippets

 2 years ago
source link: https://gist.github.com/FlorianWolters/be839c84991a789df1c6
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C++ source code snippets

Represent one byte

using Byte = std::uint8_t;

Represent a dynamic number of bytes

#include <vector>

using ByteVector = std::vector<std::uint8_t>;

Create a std::vector from a std::stringstream

#include <iostream>
#include <sstream>
#include <string>
#include <vector>

int main() {
  std::stringstream stream{"hello, world\0"};
  std::string const kString{stream.str()};
  std::vector<std::uint8_t> const kVector{kString.begin(), kString.end()};

  // Test
  for (auto const kByte : kVector) {
    std::cout << kByte;
  }
}

Write a std::vector to a std::ostream

Using std::streambuf::pubsetbuf

#include <iostream>
#include <sstream>
#include <vector>

int main() {
  std::vector<std::uint8_t> vector{'a', 'b', 'c'};
  std::stringstream stream;
  //stream.rdbuf()->pubsetbuf(reinterpret_cast<char *>(&vector[0]), vector.size());
  stream.rdbuf()->pubsetbuf(reinterpret_cast<char *>(kVector.data()), kVector.size());

  // Test
  std::cout << stream.str();
}

Using std::copy

#include <iostream>
#include <iterator>
#include <sstream>
#include <vector>

int main() {
  std::vector<std::uint8_t> vector{'a', 'b', 'c'};
  std::stringstream stream;
  std::copy(vector.begin(), vector.end(), std::ostream_iterator<std::uint8_t>(stream));

  // Test
  std::cout << stream.str() << "\n";
}

Using std::ostream.write

#include <iostream>
#include <vector>

void write_vector_to_ostream(std::ostream &ostream, std::vector<std::uint8_t> const &kVector) {
  ostream.write(reinterpret_cast<char const *>(kVector.data()), kVector.size());
}

int main() {
  // Test
  write_vector_to_ostream(std::cout, std::vector<std::uint8_t>{'a', 'b', 'c'});
}

Implementing << for std::vector

#include <iostream>
#include <iterator>
#include <vector>

template <typename T>
std::ostream& operator<<(std::ostream& os, std::vector<T> const& kVector) {
  std::copy(kVector.begin(), kVector.end(), std::ostream_iterator<T>(os));

  return os;
}

int main() {
  std::vector<std::uint8_t> const kVector{'a', 'b', 'c'};

  // Test
  std::cout << kVector << "\n";
}

Serialization

Receive "raw" data via a network socket using Boost.Asio

The length should be equal to the length of the expected message if possible.

char d1[128];
size_t bytes_transferred = sock.receive(boost::asio::buffer(d1));

std::vector<char> d2(128);
bytes_transferred = sock.receive(boost::asio::buffer(d2));

std::array<char, 128> d3;
bytes_transferred = sock.receive(boost::asio::buffer(d3));

boost::array<char, 128> d4;
bytes_transferred = sock.receive(boost::asio::buffer(d4));

Convert "raw" data to a std::istream

boost::asio::streambuf b;

// reserve 512 bytes in output sequence
boost::asio::streambuf::mutable_buffers_type bufs = b.prepare(512);

size_t n = sock.receive(bufs);

// received data is "committed" from output sequence to input sequence
b.commit(n);

std::istream is(&b);
std::string s;
is >> s;

Deserialize an object from a std::istream

Must be implemented for each class, e.g. via a DeserializableAbstract class or via external classes (preferred).

Pseudo code:

// `is` contains an input stream:
std::string last_name;
std::string first_name;
std::uint16_t age;

is >> last_name;
is >> first_name;
is >> age;

Person person{last_name, first_name, age};

Container

std::vector

Initializing a std::vector

<used_std> > C++11
std::vector<std::uint8_t> const kBytes{'a', 'b', 'c'};
<used_std> < C++11
std::uint8_t const kBytesAsArray[] = {'a', 'b', 'c'};

std::vector<std::uint8_t> const kBytes(
    kBytesAsArray,
    kBytesAsArray + sizeof(kBytesAsArray) / sizeof(kBytesAsArray[0]));

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