*cp = 'a' + (ch - 'A');
*cp = chartype('a' + (ch - 'A'));
PRInt32 ConvertCase1(char* aString,PRUint32 aCount,PRBool aToUpper){   PRInt32 result=0;  typedef char  chartype;  chartype* cp = (chartype*)aString;  chartype* end = cp + aCount-1;  while (cp <= end) {    chartype ch = *cp;    if(aToUpper) {      if ((ch >= 'a') && (ch <= 'z')) {        *cp = 'A' + (ch - 'a');      }    }    else {      if ((ch >= 'A') && (ch <= 'Z')) {        *cp = 'a' + (ch - 'A');      }    }    cp++;  }  return result;}