char[] to hex string exercise

Question

Below is my current char* to hex string function. I wrote it as an exercise in bit manipulation. It takes ~7ms on a AMD Athlon MP 2800+ to hexify a 10 million byte array. Is

Answer 1

Faster C Implmentation

This runs nearly 3x faster than the C++ implementation. Not sure why as it's pretty similar. For the last C++ implementation that I posted it took 6.8 seconds to run through a 200,000,000 character array. The implementation took only 2.2 seconds.

#include 
#include 

char* char_to_hex(const unsigned char* p_array, 
                  unsigned int p_array_len,
                  char** hex2ascii)
{
    unsigned char* str = malloc(p_array_len*2+1);
    const unsigned char* p_end = p_array + p_array_len;
    size_t pos=0;
    const unsigned char* p;
    for( p = p_array; p != p_end; p++, pos+=2 ) {
       str[pos] = hex2ascii[*p][0];
       str[pos+1] = hex2ascii[*p][1];
    }
    return (char*)str;
}

int main()
{
  size_t hex2ascii_len = 256;
  char** hex2ascii;
  int i;
  hex2ascii = malloc(hex2ascii_len*sizeof(char*));
  for(i=0; i