有重载的情况下，传参有时需要显式类型：
float float f = 1.0F double double d = 1D; decimal decimal d = 1,0M uint unit i = 1U; long long i = 1L; ulong ulong i = 1UL;
参考：https://www.jianshu.com/p/eb45efd9d3ce
C# 数值类型后缀
原文：https://www.cnblogs.com/huvjie/p/14883669.html
