哈希符号表示预处理程序命令，这些命令是在编译之前进行处理的命令，本质上会生成动态/条件代码。这些类型的命令通常用于C / C ++之类的语言中，以管理跨平台编程技术。常见用法是检查特定的环境或平台（即VBA，Windows，MacOSX等），然后实现特定于平台的代码。

The hash symbols represent a preprocessor command, which are commands that are processed prior to compilation, essentially producing dynamic / conditional code. These types of commands are often used in languages such as C/C++ to manage cross-platform programming techniques. A common usage is to check for a particular environment or platform (ie. VBA, Windows, MacOSX, etc), and then implement platform-specific code.

http://en.wikipedia.org/wiki/Preprocessor