Is 1E3 a floating point number?

1. When doing project , Encountered such a problem

 QDataStream out(m_caliFile);
                    out << m_sigGenMark<< (int)(1e3*m_amplitudeRatio) << m_freVec[m_sigGenMark]
                        << m_freVec[m_sigGenMark] << m_setAngle ;

among m_setAngle yes int Type data , Then I multiply by 1e3, Later, it is found that the data structure is four bytes more , original 1e3 Is a floating point type .

2. Another phenomenon is QDataStream The data of is big end mode binary data , Pay attention when reading data .