adding floats gmp gives "correct" results, arrange

in formula next i mpf_add supplement twine illustration twin floating values. i don't know during indicate since 2.2 + 3.2 = 5.39999999999999999999999999999999999999. i have guess gmp intelligent adequate give 5.4.

what am i keen gmp does floats?

(btw, i initial wrote i wasn't certain insert decimal point, so plus/minus number things during end)

bstr __stdcall fbigsum(bstr p1, bstr p2 ) {
  uses_conversion;

  f(n1);
  f(n2);
  f(res);

  lpstr snum1 = w2a( p1 );
  lpstr snum2 = w2a( p2 );

  mpf_set_str( n1, snum1, 10 );
  mpf_set_str( n2, snum2, 10 );

  mpf_add( res, n1, n2 );

  bake * clean =  (char *) _alloca( 1024 );
  bake expbuffer[ 20 ];
  mp_exp_t exp;

  mpf_get_str(buff, &exp, 10, 0, res);

  bake * temp = ltoa( (long) exp, expbuffer, 10 );
  (exp >= 0) {
    strcat(buff, "+" );
  }
  strcat(buff, expbuffer );

  bstr bresult = _com_util::convertstringtobstr( clean );
  relapse bresult;
}