Fourier descr iptor which is invariant to rotation and scaling

P2P connections descr iptor

类型定义符 typedef Ｃ语言不仅提供了丰富的数据类型 ， 而且还允许由用户自己定义类型说明符 ， 也就是说 允许由用户为数据类型取“别名” 。类型定义符 typedef 即可用来完成此功能。(Type delimiter typedefC language not only provides rich data types, but also allows users to define their own types by the descr iptor, that is allowed