Udp 使用示例

#include <iostream>
#include <winsock2.h>

#pragma comment(lib, "ws2_32.lib")

#include<thread>


SOCKET sendSocket;
sockaddr_in localAddr;
sockaddr_in targetAddr;

void initSocket()
{
	WSADATA wsaData;
	int result = WSAStartup(MAKEWORD(2, 2), &wsaData);
	if (result != 0) {
		std::cerr << "WSAStartup failed: " << result << std::endl;
		return ;
	}

	// 创建 UDP 套接字
	sendSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
	if (sendSocket == INVALID_SOCKET) {
		std::cerr << "Error at socket(): " << WSAGetLastError() << std::endl;
		WSACleanup();
		return ;
	}

	// （可选）绑定到特定本地端口（例如 12345）
	
	localAddr.sin_family = AF_INET;
	localAddr.sin_port = htons(12345); //发送使用此端口  接收也是使用此端口
	localAddr.sin_addr.s_addr = INADDR_ANY; // 使用任意可用的本地 IP 地址

	// 绑定套接字到本地端口
	if (bind(sendSocket, (SOCKADDR*)&localAddr, sizeof(localAddr)) == SOCKET_ERROR) {
		std::cerr << "Bind failed with error: " << WSAGetLastError() << std::endl;
		closesocket(sendSocket);
		WSACleanup();
		return ;
	}

	// 目标地址信息
	
	targetAddr.sin_family = AF_INET;
	targetAddr.sin_port = htons(8080); // 目标端口
	targetAddr.sin_addr.S_un.S_addr = inet_addr("127.0.0.1"); // 目标 IP 地址

	const char* sendData = "Hello, UDP!";



}


void sendThread()
{
	while (1)
	{
		Sleep(1000);
		int bytesSent = sendto(sendSocket, "123", 4, 0, (SOCKADDR*)&targetAddr, sizeof(targetAddr));
		std::cout << "send" << std::endl;
	}
}

void recvThread()
{
	while (1)
	{
		Sleep(100);
		unsigned long	socketMode = 1;
		ioctlsocket(sendSocket, FIONBIO, &socketMode);

		int  fromlen = sizeof(localAddr);
		char ch[64] = { 0 };
		int err = recvfrom(sendSocket, ch, 64, 0, (struct sockaddr *) &localAddr, &fromlen);	//block
		if (err > 0)
		{
			std::cout << ch << std::endl;
		}
		

	}
}



int main() 
{
	initSocket();

	std::thread th1(&sendThread);
	th1.detach();

	std::thread th2(&recvThread);
	th2.detach();

	getchar();


	closesocket(sendSocket);
	WSACleanup();

	return 0;
}

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