rationalNumber.cc

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#include "rationalNumber.h"
#include "parseTools.h"


const rationalNumber rationalNumber::Zero(0);

const rationalNumber rationalNumber::One(1);



 rationalNumber::rationalNumber(std::stringstream & ssNum)
{
        //rationalNumber res;
        #ifdef DEBUG
                std::cerr << "rationalNumber: extractFromStream" << std::endl;
                std::cerr << "ssNum: = " << ssNum.str() << std::endl;
                std::cerr << "getSign" << std::endl;    
        #endif

        ssNum >>std::ws;        

        int sign = extractSign(ssNum);

        ssNum >> numerator;


        if (ssNum.fail())
        {
                ssNum.clear();
                if (sign>0)
                {
                        throw "ssNum createFromStream failed";
                }
                else
                {
                        numerator=1;
                        denominator=1;
                }
        }

        #ifdef DEBUG
                std::cerr << ">> sign = " << sign << std::endl;
                std::cerr << ">> numerator = " << numerator << std::endl;
        #endif

        ssNum >> std::ws;

        // Vorzeichen setzen:
        numerator *= sign;
        
        #ifdef DEBUG
                std::cerr << ">> numerator" << numerator<< std::endl;
        #endif
        if (ssNum.eof() || ssNum.peek()!='/')
        {
                denominator=1;
        }
        else
        {
                extractChar(ssNum,'/');
                ssNum >> std::ws;
                int dsign = ::getSign(ssNum);

                numerator = numerator*dsign;
                ssNum >> denominator;

                if (ssNum.fail())
                {
                        ssNum.clear();
                        throw "createFromStream (extract denominator) failed";
                }
        }

        #ifdef DEBUG
                std::cerr << "rattional Number = " << (*this);
        #endif
}



int rationalNumber::extractSign(std::stringstream&  sstream)
{
        char a;
        int  sign=1;    

        int count =0;

        while (!sstream.eof() )
        {
                sstream >> std::ws;
                if (!sstream.eof())
                {
                        a=sstream.peek();
        
                        if (a=='-' || a =='+')
                        {
                                count++;
                                if (count>2)            
                                        throw "rationalNumber::extractSign three or more '+|-' in series";
                                sstream >>a;
                                if (a=='-')
                                        sign*=-1;
                        }
                        else 
                                break;
                }
                else 
                        break;
        }
        return sign;
}



rationalNumber& rationalNumber::operator+=( const rationalNumber& r2)
{
        
        int newNumerator          = this->numerator*r2.denominator  + r2.numerator*this->denominator;

        int newDenominator = denominator*r2.denominator;

        numerator       = newNumerator;
        denominator     = newDenominator;
        
        return *this;
}

bool  rationalNumber::operator==(const rationalNumber& r2) const
{
        return (numerator*r2.denominator==r2.numerator*denominator);
}

bool  rationalNumber::operator!=(const rationalNumber& r2) const
{
        return !(numerator*r2.denominator==r2.numerator*denominator);
}


std::ostream&  rationalNumber::operator<<(std::ostream & os) const
{
        os << numerator << "/" << denominator ;
        return os;
}

std::ostream &  operator<<(std::ostream & out, const rationalNumber& zahl)
{       
        return zahl.operator<<(out);
}