各种套接字接口函数都有其使用的上下文环境和参数规定。上下文环境由程序模式和程序流程决定；参数则有正确和错误之分。因此在根据错误提示信息解决错误时，应注意到这两种情况。-various socket interface function has its use in the context of environmental requirements and parameters. Environmental context by the procedures in decision process