[Boost-users] Decoding hex stream of bytes to binary form

21 Aug 2008

      Hi,

I've a small function (see below) to convert hex encoded stream of
bytes to binary stream. My question is, could anyone suggest equivalent 
function but implemented with help of Boost libraries?
I don't have any particular goal or requirement like better performance, 
simpler implementation, etc. I'm just curious what Boost components I 
can use to achieve this kind of tasks.

I've scanned the archives but there seem to be not much on 
encoding/decoding hex string, just:

http://lists.boost.org/boost-users/2007/11/32269.php

// hex-to-bin function
#include <sstream>
#include <string>
#include <vector>
typedef std::vector<unsigned char> ewkb_t;

// hexstr [in] - string with hex encoded bytes
// bytes [out] - output in binary form
void hex_to_bin(std::string const& hexstr, ewkb_t bytes)
{
     bytes.clear();
     for(std::string::size_type i = 0; i < hexstr.size() / 2; ++i)
     {
         std::istringstream iss(hexstr.substr(i * 2, 2));
         unsigned int n;
         iss >> std::hex >> n;
         bytes.push_back(static_cast<unsigned char>(n));
     }
}

Best regards,
-- 
Mateusz Loskot, http://mateusz.loskot.net
Charter Member of OSGeo, http://osgeo.org