用C++写一个UDP通信程序，分为客户端和服务端

以下是一个简单的UDP通信程序，包括了客户端和服务端的代码：

服务端：

#include <iostream>
#include <cstring>
#include <cstdlib>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
 
using namespace std;
 
const int BUF_SIZE = 1024;
 
int main(int argc, char* argv[])
{
    if(argc != 2)
    {
        cout<<"Usage: "<<argv[0]<<" <port>"<<endl;
        exit(1);
    }
 
    int serv_sock = socket(AF_INET, SOCK_DGRAM, 0);
 
    sockaddr_in serv_addr;
    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_addr.sin_port = htons(atoi(argv[1]));
 
    bind(serv_sock, (sockaddr*)&serv_addr, sizeof(serv_addr));
 
    sockaddr_in clnt_addr;
    socklen_t clnt_addr_len = sizeof(clnt_addr);
 
    char buffer[BUF_SIZE];
    while(true)
    {
        int str_len = recvfrom(serv_sock, buffer, BUF_SIZE, 0, (sockaddr*)&clnt_addr, &clnt_addr_len);
        sendto(serv_sock, buffer, str_len, 0, (sockaddr*)&clnt_addr, clnt_addr_len);
    }
 
    close(serv_sock);
 
    return 0;
}

客户端：

#include <iostream>
#include <cstring>
#include <cstdlib>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
 
using namespace std;
 
const int BUF_SIZE = 1024;
 
int main(int argc, char* argv[])
{
    if(argc != 3)
    {
        cout<<"Usage: "<<argv[0]<<" <IP> <port>"<<endl;
        exit(1);
    }
 
    int clnt_sock = socket(AF_INET, SOCK_DGRAM, 0);
 
    sockaddr_in serv_addr;
    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = inet_addr(argv[1]);
    serv_addr.sin_port = htons(atoi(argv[2]));
 
    while(true)
    {
        char message[BUF_SIZE];
        cout<<"Enter message to send: ";
        cin>>message;
        sendto(clnt_sock, message, strlen(message), 0, (sockaddr*)&serv_addr, sizeof(serv_addr));
 
        sockaddr_in from_addr;
        socklen_t from_addr_len = sizeof(from_addr);
        char buffer[BUF_SIZE];
        int str_len = recvfrom(clnt_sock, buffer, BUF_SIZE, 0, (sockaddr*)&from_addr, &from_addr_len);
        buffer[str_len] = 0;
        cout<<"Message from server: "<<buffer<<endl;
    }
 
    close(clnt_sock);
 
    return 0;
}

这个程序简单地实现了一个服务端和客户端之间的UDP通信。服务端接收来自客户端的消息，然后将其原封不动地发送回客户端。客户端循环地读取用户输入并将其发送到服务端，然后等待来自服务端的响应。