windows多客户端socket tcp通讯

#include <iostream>
#include <thread>
#include <string>
#include <WinSock2.h>
#include <Ws2tcpip.h>
#pragma comment(lib, "ws2_32.lib")

using std::cin;
using std::cerr;
using std::cout;
using std::endl;
using std::flush;

const int SEND_BUF_SIZE = 256;
bool b_running = true;
bool b_send = false;

//接收服务器返回的数据
void t_read_result(SOCKET sock_client){
	int recv_result = 0;
	char _buf[SEND_BUF_SIZE];
	while (b_running) {
		recv_result = recv(sock_client, _buf, SEND_BUF_SIZE, 0);
		if (strlen(_buf) > 0) {
			cout << "bytes: " << strlen(_buf) << " receive_msg: " << _buf << endl;//feedback from server
			memset(_buf, 0, SEND_BUF_SIZE);
		}
		if (recv_result == 0) {
			cout << "bytes: " << strlen(_buf) << " connection closed..." << endl;
		}
		if (recv_result < 0) {
			cerr << "recv() function failed with error: " << WSAGetLastError() << "\n";
			closesocket(sock_client);
			WSACleanup();
			system("pause");
			return;
		}
	}
}

//向服务器发送数据
bool send_data(SOCKET client)
{
	while (b_running){
		std::string input;
		cin >> input;
		//int error=send(SOCKET s, const void * msg, int len, unsigned int flags)//send()用来将数据由指定的socket通信
		//s为已建立好连接的socket，msg数据内容，len数据长度，参数flags一般设0
		//成功则返回实际传送出去的字符数，失败返回-1，错误原因存于error
		int result = send(client, input.c_str(), static_cast<int>(input.size()), 0);
		if (SOCKET_ERROR == result)
		{
			int error = WSAGetLastError();//错误代码
			if (WSAEWOULDBLOCK == error)
			{
				continue;
			}
			else if (WSAENETDOWN == error || WSAETIMEDOUT == error || WSAECONNRESET == error)
			{
				return false;
			}
		}
	}
	return true;		//发送成功
}

int main()
{
	WSADATA wsdata;
	if (WSAStartup(MAKEWORD(2, 2), &wsdata) != 0)
	{
		return 0;
	}

	SOCKET client = socket(AF_UNSPEC, SOCK_STREAM, IPPROTO_TCP);
	if (client == INVALID_SOCKET)
	{
		printf("创建套接字失败!");
		return 0;
	}

	sockaddr_in addr;
	addr.sin_family = AF_INET;
	addr.sin_port = htons(1024);//串口（需与服务器一致）
	addr.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");//IP
	if (connect(client, (struct sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR)
	{ 
		printf("连接服务器失败!");
		closesocket(client);
		return 0;
	}

	std::thread read_result(t_read_result, std::ref(client));
	read_result.detach();

	send_data(client);

	closesocket(client);
	WSACleanup();
	return 0;

}