【C++】TCP/IP协议 实现客户端和服务器通讯。

借鉴，源码非原创，来自MagicSaring的一个简单的TCP通信程序Demo。

一、客户端源码：

#include <WinSock2.h>
#include <iostream>
#include "client.h"
using namespace std;

#pragma comment(lib, "WS2_32.lib")
//表示链接WS2_32.lib这个库。
#define  PORT 1024

int connectToServer(char* send_msg)
{
	SOCKET sock_client;
	struct sockaddr_in server_addr;
	int addr_len = sizeof(struct sockaddr_in);
	char msgbuffer[1000];
	memset(msgbuffer, 0, sizeof(msgbuffer));
	// 初始化 winsock2.dll[12/27/2017 MagicScaring]
	WSADATA wsaData;
	WORD wVersionRequested = MAKEWORD(2, 2);        //生成版本号
	if (WSAStartup(wVersionRequested, &wsaData) != 0)
	{
		cout << "加载 winsock.dll失败" << endl;
		return 0;
	}
	// 创建套接字 [12/27/2017 MagicScaring]
	if ((sock_client = socket(AF_INET, SOCK_STREAM, 0)) == SOCKET_ERROR)
	{
		cout << "创建套接字失败! 错误代码:" << WSAGetLastError() << endl;
		WSACleanup();                   //注销WinSock动态链接库
		return 0;
	}
	// 填写服务器地址 [本机地址]
	char IP[20] = { "192.168.1.106" };
	/*char IP[20];
	cout << "输入服务器地址:" << endl;
	cin >> IP;*/
	memset((void*)&server_addr, 0, sizeof(server_addr));
	server_addr.sin_family = AF_INET;
	server_addr.sin_port = htons(PORT);
	server_addr.sin_addr.s_addr = inet_addr(IP);

	// 与服务器建立连接 [2018/5/22]
	if (connect(sock_client, (struct sockaddr*)&server_addr, addr_len) == SOCKET_ERROR)
	{
		cout << "连接失败! 错误代码:" << WSAGetLastError() << endl;
		closesocket(sock_client);
		WSACleanup();
		return 0;
	}
	while (true)
	{
		int size;
		if ((size = recv(sock_client, msgbuffer, sizeof(msgbuffer), 0)) == SOCKET_ERROR)
		{
			cout << "接收信息失败！ 错误代码：" << WSAGetLastError() << endl;
			closesocket(sock_client);
			WSACleanup();
			return 0;
		}
		else if (size == 0)
		{
			cout << "对方已关闭连接" << endl;
			closesocket(sock_client);
			WSACleanup();
			return 0;
		}
		else
		{
			cout << "The message from Server:" << msgbuffer << endl;
		}
		//char send_msg[1000] = { "Hello server" };
		//send_msg是要发送的数据，是char指针
		if ((size = send(sock_client, send_msg, sizeof(send_msg), 0)) == SOCKET_ERROR)
		{
			cout << "发送信息失败! 错误代码:" << WSAGetLastError() << endl;
		}
		else if (size == 0)
		{
			cout << "对方已关闭连接" << endl;
		}
		else
		{
			cout << "信息发送成功" << endl;
		}

	}
	closesocket(sock_client);
	WSACleanup();

	return 0;
}

二、主程序调用

connectToServer(s_buf);

注意主程序头文件库的顺序，winSock2.h放在最前面。

至于为什么，I dont know.

三、服务器源码

#include "stdafx.h"
#include <iostream>
#include <WinSock2.h>
using namespace std;

#pragma comment(lib, "WS2_32.lib")
//表示链接WS2_32.lib这个库。
#define  PORT 1024

int main()
{
	SOCKET sock_server, newsock;
	struct sockaddr_in server_addr, client_addr;
	char msg[] = { "Hello client" };
	// 初始化 winsock2.dll[12/27/2017 MagicScaring]
	WSADATA wsaData;
	WORD wVersionRequested = MAKEWORD(2, 2);        //生成版本号
	if (WSAStartup(wVersionRequested, &wsaData) != 0)
	{
		cout << "加载 winsock.dll失败" << endl;
		return 0;
	}
	// 创建套接字 [12/27/2017 MagicScaring]
	if ((sock_server = socket(AF_INET, SOCK_STREAM, 0)) == SOCKET_ERROR)
	{
		cout << "创建套接字失败! 错误代码:" << WSAGetLastError() << endl;
		WSACleanup();                   //注销WinSock动态链接库
		return 0;
	}
	// 填写需要绑定的本地地址 []
	int addr_len = sizeof(struct sockaddr_in);
	memset((void*)&server_addr, 0, sizeof(server_addr));
	server_addr.sin_family = AF_INET;
	server_addr.sin_port = htons(PORT);
	server_addr.sin_addr.s_addr = htonl(INADDR_ANY);

	if (bind(sock_server, (struct sockaddr*)&server_addr, addr_len) != 0)
	{
		cout << "绑定失败!错误代码:" << WSAGetLastError() << endl;
		closesocket(sock_server);               //关闭已连接套接字
		WSACleanup();                           //注销WinSock动态链接库
		return 0;
	}

	// 开始监听 [12/27/2017 MagicScaring]
	if (listen(sock_server, 0) != 0)
	{
		cout << "listen调用失败!错误代码:" << WSAGetLastError() << endl;
		closesocket(sock_server);
		WSACleanup();
		return 0;
	}
	else
	{
		cout << "listening...." << endl;
	}
	// 循环:接收连接请求并收发数据 [12/27/2017 MagicScaring]
	int size;
	while (true)
	{
		if ((newsock = accept(sock_server, (struct sockaddr *)&client_addr, &addr_len)) == INVALID_SOCKET)
		{
			cout << "accept 函数调用失败! 错误代码:" << WSAGetLastError() << endl;
			break;
		}
		else
		{
			cout << "成功接收到一个连接请求!" << endl;
			size = send(newsock, msg, sizeof(msg), 0);
			if (size == SOCKET_ERROR)
			{
				cout << "发送信息失败! 错误代码:" << WSAGetLastError() << endl;
				closesocket(newsock);
				continue;
			}
			else if (size == 0)
			{
				cout << "对方已关闭连接" << endl;
				closesocket(newsock);
				continue;
			}
			else
			{
				cout << "信息发送成功" << endl;
			}
			size = recv(newsock, msg, sizeof(msg), 0);
			if (size == SOCKET_ERROR)
			{
				cout << "接收信息失败！ 错误代码：" << WSAGetLastError() << endl;
				closesocket(newsock);
				WSACleanup();
				return 0;
			}
			else if (size == 0)
			{
				cout << "对方已关闭连接" << endl;
				closesocket(newsock);
				WSACleanup();
				return 0;
			}
			else
			{
				
				cout << "The message from Client:" << msg<< endl;

			}
		}
	}

	return 0;
}