Convert Hex String to Hex Value

Question

I have a large hex string

abcdef...

and I want to convert it to

0xab 0xcd 0xef 

Are there any functions

Answer 1

You can do this using string streams.

#include 
#include 
#include 

int main( int , char ** )
{
  const char *str = "AFAB2591CFB70E77C7C417D8C389507A5";
  const char *p1  = str;
  const char *p2  = p1;

  std::vector output;

  while( *p2 != NULL ) {
    unsigned short byte;

    ++p2;
    if( *p2 != NULL ) {
      ++p2;
    }

    std::stringstream sstm( std::string( p1, p2 ) );

    sstm.flags( std::ios_base::hex );
    sstm >> byte;

    output.push_back( byte );

    p1 += 2;
  }

  for( std::vector::const_iterator it = output.begin(); it != output.end(); ++it ) {
    std::cout << std::hex << std::showbase << *it << "\t" << std::dec << std::noshowbase << *it << "\n";
  }

  std::cout << "Press any key to continue ...";
  std::cin.get();
}

Note that if you use unsigned char instead of unsigned short the conversion from stringstream attempts to convert it into an ASCII character and it doesn't work.