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 by the user "alias data type". The type definition typedef can be used to complete this function.)