/***      ---结构体---**      #include <sys/socket.h>*      struct sockaddr {*              unsigned short sa_family;*              char sa_data[14];*      }**      #include <netinet/in.h>*      struct sockaddr_in {*              short int sin_family;           //sa_family_t*              unsigned short sin_port;        //in_port_t*              struct in_addr sin_addr;*              unsigned char sin_zero[8];*      }**      #include <netinet/in.h>*      sturct in_addr {*              uint32_t s_addr;*      }*//*** --IP转换---*  ulong inet_addr(const char *ip);    //将一个点分十进制的ip转换成一个网络字节序的长整型数*  int inet_aton(const char *ip, struct in_addr *inp);         //将一个字符串ip转换成一个32位的网络字节序*  char *inet_ntoa(sturct in_addr in);*//*** ---域名转换---*  #include <netdb.h>*  struct hostent{*              char *h_name;*              char **h_aliases;*              short h_addrtype;*              short h_length;*              char **h_addr_list;*  }*  #define h_addr h_addr_list[0]*      sturct hostent *h = gethostbyname(const char *hostname); //结果会存在resbuf里边**//*** ---字节序转换---*  #include <arpa/inet.h>*  uint32_t htonl(uint32_t hostlong)*  uint32_t ntohl(uint32_t hostlong)*      uint16_t htons(unit16_t hostshort)*      uint16_t ntohs(uint16_t hostshort)*//*** *//*** int socket(int domain, int type, int protocol);* int bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen);* int listen(int sockfd, int backlog);* int connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen);* int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen);* int send(int sockfd, const void *buf, size_t len, int flags);* int recv(int sockfd, void *buf, size_t len, int flags);*/