UDP单播

CMakeLists.txt文件中添加如下行：

link_libraries(ws2_32)

1.发送端

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

#pragma comment(lib, "Ws2_32.lib")  // Link with ws2_32.lib

int main() {
     1.Initialize winsock
    WSADATA wsaData;
    int iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (iResult != NO_ERROR) {
        wprintf(L"WSAStartup failed with error: %d\n", iResult);
        return 1;
    }

     2.Create a socket for sending data
    SOCKET SendSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
    if (SendSocket == INVALID_SOCKET) {
        wprintf(L"socket failed with error: %1d\n", WSAGetLastError());
        WSACleanup();
        return 1;
    }

     3.Set up the RecvAddr structure with the IP address of the receiver (in this example case "192.168.1.1")
     and the specified port number.
    sockaddr_in RecvAddr = {0};
    unsigned short Port = 27015;
    RecvAddr.sin_family = AF_INET;
    RecvAddr.sin_port = htons(Port);
    RecvAddr.sin_addr.s_addr = inet_addr("127.0.0.1");

     4.Send a datagram to the receiver
    wprintf(L"Sending a datagram to the receiver...\n");
    char sendBuf[1024]="Hello";
    int BufLen = 1024;
    iResult = sendto(SendSocket, sendBuf, BufLen, 0, reinterpret_cast<SOCKADDR *>(&RecvAddr), sizeof(RecvAddr));
    if (iResult == SOCKET_ERROR) {
        wprintf(L"sendto failed with error: %d\n", WSAGetLastError());
        closesocket(SendSocket);
        WSACleanup();
        return 1;
    }

     5.When the application is finished sending, close the socket.
    wprintf(L"Finished sending. Closing socket. \n");
    iResult = closesocket(SendSocket);
    if (iResult == SOCKET_ERROR) {
        wprintf(L"closesocket failed with error: %d\n", WSAGetLastError());
        WSACleanup();
        return 1;
    }

     6.Clean up and quit.
    wprintf(L" Exiting.\n");
    WSACleanup();
    return 0;
}

2.接收端代码

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

#pragma comment(lib, "Ws2_32.lib")  // Link with ws2_32.lib

int main() {
     1.Initialize winsock
    WSADATA wsaData;
    int iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (iResult != NO_ERROR) {
        wprintf(L"WSAStartup failed with error: %d\n", iResult);
        return 1;
    }

     2.Create a receiver socket to receive datagrams
    SOCKET RecvSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
    if (RecvSocket == INVALID_SOCKET) {
        wprintf(L"socket failed with error: %1d\n", WSAGetLastError());
        return 1;
    }

     3.Bind the socket to any address and the specified port.
    sockaddr_in RecvAddr = {0};
    unsigned short Port = 27015;
    RecvAddr.sin_family = AF_INET;
    RecvAddr.sin_port = htons(Port);
    RecvAddr.sin_addr.s_addr = htonl(INADDR_ANY);

    iResult=bind(RecvSocket,reinterpret_cast<SOCKADDR*>(&RecvAddr), sizeof(RecvAddr));
    if (iResult != 0) {
        wprintf(L"bind failed with error: %d\n", WSAGetLastError());
        return 1;
    }

     4.Call the recvfrom function to receive datagrams on the bound socket.
    wprintf(L"Receiving datagrams...\n");
    char RecvBuf[1024];
    int RecvAddrSize=sizeof(RecvAddr);
    iResult = recvfrom(RecvSocket, RecvBuf, sizeof(RecvBuf), 0, reinterpret_cast<SOCKADDR *>(&RecvAddr), &RecvAddrSize);
    if (iResult == SOCKET_ERROR) {
        wprintf(L"recvfrom failed with error: %d\n", WSAGetLastError());
    } else{
        printf("%s\n",RecvBuf);
    }

     5.Close the socket when finished receiving datagrams
    wprintf(L"Finished receiving. Closing socket. \n");
    iResult = closesocket(RecvSocket);
    if (iResult == SOCKET_ERROR) {
        wprintf(L"closesocket failed with error: %d\n", WSAGetLastError());
        WSACleanup();
        return 1;
    }

     6.Clean up and quit.
    wprintf(L" Exiting.\n");
    WSACleanup();
    return 0;
}

执行结果：