Read contents of a file as hex in C

Question

I have a file with hex values saved as hex.txt which has

9d ff d5 3c 06 7c 0a

Now I need to convert it to a character array as

Answer 1

I can offer a code like this. Add proper includes.

unsigned char * read_file(FILE * file) //Don't forget to free retval after use
{
   int size = 0;
   unsigned int val;
   int startpos = ftell(file);
   while (fscanf(file, "%x ", &val) == 1)
   {
      ++size;
   }
   unsigned char * retval = (unsigned char *) malloc(size);
   fseek(file, startpos, SEEK_SET); //if the file was not on the beginning when we started
   int pos = 0;
   while (fscanf(file, "%x ", &val) == 1)
   {
      retval[pos++] = (unsigned char) val;
   }
   return retval;
}