怎样用5毫升的量杯和3毫升的量杯量出4毫升的水用c语言写出来解决办法

#include "stdio.h"

#define min( x, y ) ((( x ) < ( y )) ? ( x ) : ( y ))

class CGlass
{
public:
    CGlass( int nSize, int nWater = 0 ) : m_nSize( nSize ), m_nWater( nWater ){}
    ~CGlass(){}

    void Eject( int nWater = 0 )
    {
        if( nWater == 0 )
            m_nWater = 0;
        else
        {
            m_nWater -= nWater;
            if( m_nWater < 0 )
                m_nWater = 0;
        }
    }
    void Inject( int nWater = 0 )
    {
        if( nWater == 0 )
            m_nWater = m_nSize;
        else
        {
            m_nWater += nWater;
            if( m_nWater > m_nSize )
                m_nWater = m_nSize;
        }
    }

    int GetSize() const  { return m_nSize; }
    int GetWater() const { return m_nWater; }

    int operator>>( CGlass& other )
    {
        int w = min( m_nWater, ( other.GetSize() - other.GetWater()));
        Eject( w );
        other.Inject( w );
        return m_nWater;
    }
    int operator<<( CGlass& other )
    {
        int w = min( m_nSize - m_nWater, other.GetWater());
        Inject( w );
        other.Eject( w );
        return m_nWater;
    }

protected:
    int m_nSize;
    int m_nWater;
};

int _tmain(int argc, _TCHAR* argv[])
{
    CGlass g5( 5, 5 );
    CGlass g3( 3 );

    g5 >> g3;
    g3.Eject();

    g5 >> g3;
    g5.Inject();
    g5 >> g3;

    printf( "G5 left water is : %d", g5.GetWater());

    getchar();
    return 0;
}