How to convert Byte Array to Hexadecimal String in C++?

Question

I am looking for a fastest way to convert a byte array of arbitrary length to a hexadecimal string. This question has been fully answered here at StackOverflow for C#. Some solutions in C++ can be found here.

Are there any "turnkey" or "ready-made" solutions to a problem? C-style solutions are welcome.

Answer 1

#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
#include <iterator>
#include <sstream>
#include <iomanip>

int main() 
{
  std::vector<unsigned char> v;

  v.push_back( 1 );
  v.push_back( 2 );
  v.push_back( 3 );
  v.push_back( 4 );

  std::ostringstream ss;

  ss << std::hex << std::uppercase << std::setfill( '0' );
  std::for_each( v.cbegin(), v.cend(), [&]( int c ) { ss << std::setw( 2 ) << c; } );

  std::string result = ss.str();

  std::cout << result << std::endl;
  return 0;
}

Or, if you've got a compiler that supports uniform initialization syntax and range based for loops you can save a few lines.

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

int main()
{
  std::vector<unsigned char> v { 1, 2, 3, 4 };
  std::ostringstream ss;

  ss << std::hex << std::uppercase << std::setfill( '0' );
  for( int c : v ) {
    ss << std::setw( 2 ) << c;
  }

  std::string result = ss.str();
  std::cout << result << std::endl;
}