Double in String umwandeln

void doubleToStr9(const char* str, double flpNumber, Int numFractDigits)
{ int  longNumber;
  double flpIP, zeros, round;
  Int i, remainder, strLen;
  Char sign = ' ';                 


  if (numFractDigits < 0 || numFractDigits > 9)
    FrmCustomAlert(ErrorAlert, "Error in doubleToStr9.", "", " ");


  if (flpNumber < 0.0)
    { flpNumber = -flpNumber;
      sign = '-';
    }


  zeros = 1.0;
  for (i=0; i<numFractDigits; i++)
     zeros *= 10;


  round = 0.5/zeros;
  flpNumber += round;
  flpIP = (Long) flpNumber;
  flpNumber = flpNumber - flpIP;






  str[0] = sign;
  StrIToA(&str[1], (Long) flpIP);
  strLen = StrLen(str);
  str[strLen] = '.';
  str[numFractDigits+strLen+1] = '\0';


  longNumber = flpNumber * zeros;  


  for (i=numFractDigits+strLen; i>strLen; i--) 
    { remainder = longNumber % 10;
       str[i] = remainder + 0x30; //diese Zeile scheint das Problem zu sein
      longNumber /= 10;
    }
}

char        buf[40];
MemHandle h;
double    cnt;
FormPtr   frm = FrmGetFormPtr(myFormID);
UInt16	  obj = FrmGetObjectIndex(frm, myFieldID);
FieldPtr  fld = (FieldPtr)FrmGetObjectPtr(frm, obj);
Char	  *p = FldGetTextPtr(fld);


cnt =  strToDouble(p);

cnt += val;


if(cnt >= 0 && cnt < 100){
	doubleToStr(buf,cnt);
	h = MemHandleNew(StrLen(buf) + 1);
	StrCopy((Char *) MemHandleLock(h), buf);
	FldSetTextHandle(fld,h);
	FldDrawField(fld);
	MemHandleUnlock(h);
}

FormPtr 	frm = FrmGetFormPtr(myFormID);
UInt16	obj = FrmGetObjectIndex(frm, myFieldID);
FieldPtr	fld = (FieldPtr)FrmGetObjectPtr(frm, obj);
CharPtr		p;
VoidHand	h;
double cnt;


cnt = strToDouble(GetField(myFormID,myFieldID));

cnt += val;


if(cnt >= 0 && cnt < 100){
	h = (VoidHand)FldGetTextHandle(fld);		
	p = (CharPtr) MemHandleLock (h);
	doubleToStr9(p,cnt,1);
	MemHandleUnlock (h);

	FldSetTextHandle (fld, (Handle)h);
	FldDrawField(fld);
}