tcp_non_block_client.cpp

#include <cstdio>
#include <cstring>
#include <winsock.h>

#define MAXLINE 1024

int main() {

	SOCKET        	sd;
	struct sockaddr_in serv{};
	char  		str[1024]="How are you?";
	WSADATA 		wsadata;

	WSAStartup(0x101,(LPWSADATA) &wsadata); // 呼叫 WSAStartup() 註冊 WinSock DLL 的使用

	sd=socket(AF_INET, SOCK_STREAM, 0); //開啟一個 TCP socket.

	serv.sin_family       = AF_INET;
	serv.sin_addr.s_addr  = inet_addr("127.0.0.1");
	serv.sin_port         = htons(5678);

	connect(sd, (LPSOCKADDR) &serv, sizeof(serv)); // 連接至 echo server
	printf("Client has connected to Server.\n");
	printf("Waiting 10 secs on purpose...\n");
	Sleep(10000); // 建立連線後，刻意停頓， 觀察 recv()是否block

	while (true) {  //每隔3秒，週期送出
		Sleep(3000);
		send(sd, str, strlen(str)+1, 0);

		int nError=WSAGetLastError();
		if(nError!=WSAEWOULDBLOCK && nError!=0)
		{
			printf("Winsock error code:%d\n",nError);
			printf("Disconnected!");
			// Close our socket entirely
			closesocket(sd);
			break;
		}
		printf("Send every 3 secs: %s\n" ,str);
	}
	closesocket(sd); //關閉TCP socket
	WSACleanup();  // 結束 WinSock DLL 的使用

	return 0;
}