通过现有的人口数据结构特点，对其进行拟合分析后进行长短期的预测-Population data through the existing structural features, their post-fitting analysis of the short and long-term prediction

c++类实现人口统计，计算出生率，死亡率，增长率等等。-this is a population calculate program,have function bornrate(),deadrate().