阅读 C 库的套接字接口的代码,我发现:
/* Types of sockets. */
enum __socket_type
{
SOCK_STREAM = 1, /* Sequenced, reliable, connection-based
byte streams. */
#define SOCK_STREAM SOCK_STREAM
SOCK_DGRAM = 2, /* Connectionless, unreliable datagrams
of fixed maximum length. */
#define SOCK_DGRAM SOCK_DGRAM
...
这个“成语”在 bits/socket.h 中使用。我只是好奇,这些宏的目的是什么?