have a question about Sample Class

[pdycp3]

Sample::Sample(Sample* samples)
{
_dataset=samples->_dataset;
_labels=samples->_labels;
_classNum=samples->getClassNum();
_featureNum=samples->getFeatureNum();
_sampleNum=samples->getSampleNum();
_selectedSampleNum=samples->getSelectedSampleNum();
_selectedFeatureNum=samples->getSelectedFeatureNum();
_sampleIndex=samples->getSampleIndex();
_featureIndex=samples->getFeatureIndex();
}
Sample::~Sample()
{
_sampleIndex=NULL;
_featureIndex=NULL;
}
Is it safe to write this way