Clients accessing the daytime service (TCP)

For the first time to use “winsock.in” May cause some functions to be unavailable , Solutions refer to Blog

/*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";		// The client and server are on the same host 
	string service = "daytime";	// Standard service name 
	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 To establish a socket in the environment, you must first call 
		//errexit("WSAStartup failed\n");
	TCPdaytime(host.c_str(), service.c_str());	// Completion time request service 
	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 text
	SOCKET s;				//socket descriptor
	int cc;					//recv character count
	s = connectTCP(host, service);		// establish TCP Socket and connect to the server 
	cc = recv(s, buf, LINELEN, 0);		// Complete data acceptance 
	while (cc != SOCKET_ERROR and cc > 0)
	{
    
		buf[cc] = '\0';
		(void)fputs(buf, stdout);
		cc = recv(s, buf, LINELEN, 0);
	}
	closesocket(s);
}

Reference resources MOOC Take the computer network open class of Harbin Institute of technology