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 longsocketMode = 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;
}

!

原文地址：https://blog.csdn.net/u013174817/article/details/145097365

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