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TxqFloatingDecimal.h

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//---------------------------------------------------------------------------
//
// File:    TxqFloatingDecimal.h
//
// Purpose:  Determines the exponent and digits of a double
//
// Version: $Id: TxqFloatingDecimal.h,v 1.6 2001/10/12 18:51:23 kgl Exp $
//
// This class name comes from the FloatingDecimal.java class
//
//---------------------------------------------------------------------------

#ifndef TXQ_FLOATINGDECIMAL_H
#define TXQ_FLOATINGDECIMAL_H

// system includes
#include <cmath>
#if defined(_MSC_VER)
#include <cfloat>
#else
#include <float.h>
#endif

// txmath includes
#include <TxThroughStream.h>

// Qt includes
#include <qstring.h>

class TxqFloatingDecimal
{

public:

  TxqFloatingDecimal(double num) {
     if (num < 0.0 ) sign =-1;
     else sign = 1;
     number = fabs(num);
     numDigits=3;
     reformat();
  }

  TxqFloatingDecimal(double num, int digits) {
    if (num < 0.0 ) sign =-1;
    else sign = 1;
    number = fabs(num);
    numDigits=digits;
    reformat();
  }

  TxqFloatingDecimal(float num) {
    TxqFloatingDecimal((double) num);
  }

  int getSign() {
    return sign;
  }

  int getExponentSign() {
    if ( (number < 1.0) && (number != 0) ) return -1;
    if (number >= 10.0) return 1;
    else return 0;
  }

  int getExponent() {
    return abs(exponent);
  }

  QString getStringDigits() {
    return stringNumber;
  }

  int getDigit() {
    int inum;
    if (stringNumber[stringIndex].isDigit()){
     inum = stringNumber[stringIndex].digitValue();
     stringIndex++;
    }
    else inum = 0;
    return inum;
  }

  double getNumber() {
    return number;
  }

  void setNumDigits(int n) {
    numDigits=n;
    reformat();
  }
 
  bool isNegative() {
    if (getSign() == -1) return true;
    else return false;
  }

  bool isExceptional() {
    if ( ( (number < DBL_MIN) && (number < 0) )
        || (number > DBL_MAX) ) return true;
    else return false;
  }

 ~TxqFloatingDecimal(){}

private:

  void reformat() {

// always use + number
    double a = fabs(number);
    stringIndex = 0;

// if the number is 0:
    if (a == 0.0)  {
      exponent = 0;
      reformNumber = 1;
      digitNumber = a;
      stringNumber = "0";
      for (int i=1; i<=numDigits; i++)
        stringNumber = stringNumber + "0";
      return;
    }

// compute the sign of the exponent
// (this is not good to use as the exponent
//  because of round-off errors)
    if (a < DBL_MIN) a = DBL_MIN;
    double dexponent = (log10(a));
    posExp=true;
    if (dexponent < 0.0 ) posExp=false;

// temps contains the number as a string 
//   with digits, decimal point
//   and possibly exponent (e)
    QString snumber;
    QString temps = snumber.number(a, 'g', numDigits);

// determine if exponent (e) is in the string
//  this will be true if the number is below the precision
//   (numDigits)
//  from QString.number
// if e is not in the string, then must determine the exponent
//  by counting

    bool countE = true;
    if ( temps.contains("e") ) {
      countE = false;
    }

// if positive exponent, 
//  and need to count the decimal places, then
//  start at -1
//  else start at 0

    int i=0;
    if (posExp) exponent=-1;
    else exponent = 0;
    pastDecimal=false;
    pastFirstDecimal=false;

// loop through all items in the temps string
//  break the while loop by setting i outside of the
//  temps range

    while(!temps[i].isNull()) {

// get the exponent if "e" is present
//  at the correct location
       QChar e = temps[i];
       if (e == "e") { 
         // next is sign
         i++;
         // beginning of exponent
         i++;
         QString sExp;
         while(!temps[i].isNull()) {
           if(temps[i].isDigit()) sExp = sExp + temps[i];
           i++;
         }
         exponent = sExp.toInt();
         i=temps.length()+1;
       }

       else {

// must count for exponent number
//  positve exponent
         if (countE) {
           if (posExp) {
             QChar anum = temps[i];

//  search for decimal point
             if (anum == ".") {
               i++;
               anum = temps[i];
               pastDecimal = true;
             }

// increment exponent if not past decimal point
             if(anum.isDigit()) {
               stringNumber = stringNumber + anum;
               if(!pastDecimal) exponent++;
             }
             else {
               i=temps.length()+1;
             }
           }

// negative exponent
           else {
             QChar anum = temps[i];
             if (anum == ".") {
               i++;
               anum = temps[i];
               pastDecimal = true;
             }
             if (pastDecimal && !pastFirstDecimal) {
               if (!temps[i].isNull()) exponent--;
             }
             if (anum != "0") {
               if(anum.isDigit()) stringNumber = stringNumber + anum;
               pastFirstDecimal = true;
             }
             else if (pastFirstDecimal)  {
               if(anum.isDigit()) stringNumber = stringNumber + anum;
             }
           }
         }

// "e" is not present yet, but not counting for the exponent value
//  if the character is a number, add it to the stringNumber

         else {
           if(temps[i].isDigit()) stringNumber = stringNumber + temps[i];
         }
         i++;
       }
    }
  }

/*
 *  Class data members.
 */
  double reformNumber;

  double digitNumber;

  QString stringNumber;

  int stringIndex;

  int exponent;

  double number;

  int sign;

  int numDigits;

  bool pastDecimal;

  bool pastFirstDecimal;

  bool posExp;

};
#endif

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