首次使用“winsock.in”可能导致部分函数不可用，解决方法参考博客
/*TCPdaytime*/#include<cstdlib>#include<cstdio>#include<winsock.h>#include<string>using namespace std;void TCPdaytime(const char*,const char*);void errexit(const char*,...);SOCKET connectTCP(const char*, const char*);#define LINELEN 128#define WSVERS MAKEWORD(2,0)/*main - TCP client for DAYTIME serive*/int main(int argc, char* argv[]){string host = "localhost";//客户端和服务器端位于同一主机string service = "daytime";//标准服务名WSADATA wsadata;switch (argc){case 1:host = "localhost";break;case 3:service = argv[2];/* FALL THROUGH */case 2:host = argv[1];break;default:fprintf(stderr, "usage:TCPdaytime [host [port]]\n");exit(1);}if (WSAStartup(WSVERS, &wsadata) != 0)//Win环境下建立套接字必须先调用//errexit("WSAStartup failed\n");TCPdaytime(host.c_str(), service.c_str());//完成时间请求服务WSACleanup();return 0;}/*TCPdaytime - invoke Daytime on specified host and print results*/void TCPdaytime(const char* host, const char* service){char buf[LINELEN + 1];//buffer for one line of textSOCKET s;//socket descriptorint cc;//recv character counts = connectTCP(host, service);//创建TCP套接字并于服务器连接cc = recv(s, buf, LINELEN, 0);//完成数据接受while (cc != SOCKET_ERROR and cc > 0){buf[cc] = '\0';(void)fputs(buf, stdout);cc = recv(s, buf, LINELEN, 0);}closesocket(s);}
参考MOOC上哈尔滨工业大学的计算机网络公开课
