Linux 中 C++ 中的 UDP

#include<iostream>
#include <arpa/inet.h>
#include <unistd.h>
#include<string.h>

using namespace std;

int main()
{
    int sockfd;
    struct sockaddr_in serv_addr, client_addr;
    socklen_t client_addr_len;
    char buffer[1024];

    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (sockfd < 0) {
        cout << "socket error"<< endl;
        return -1;
    }

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(8888);

    if (bind(sockfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) < 0) {
        cout << "bind error"<< endl;
        return -1;
    }

    client_addr_len = sizeof(client_addr);
    int n = recvfrom(sockfd, buffer, sizeof(buffer), 0, (struct sockaddr*)&client_addr, &client_addr_len);
    if (n < 0) {
        cout << "recvfrom error"<< endl;
        return -1;
    }

    buffer[n] = '\0';
    cout << "receive from client: "<< buffer<< endl;

    n = sendto(sockfd, "hello client", strlen("hello client"), 0, (struct sockaddr*)&client_addr, client_addr_len);
    if (n < 0) {
        cout << "sendto error"<< endl;
        return -1;
    }

    close(sockfd);
    return 0;
}

#include<iostream>
#include <arpa/inet.h>
#include <unistd.h>
#include<string.h>

using namespace std;

int main()
{
    int sockfd;
    struct sockaddr_in serv_addr;
    char buffer[1024];

    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (sockfd < 0) {
        cout << "socket error"<< endl;
        return -1;
    }

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
    serv_addr.sin_port = htons(8888);

    int n = sendto(sockfd, "hello server", strlen("hello server"), 0, (struct sockaddr*)&serv_addr, sizeof(serv_addr));
    if (n < 0) {
        cout << "sendto error"<< endl;
        return -1;
    }

    n = recvfrom(sockfd, buffer, sizeof(buffer), 0, NULL, NULL);
    if (n < 0) {
        cout << "recvfrom error"<< endl;
        return -1;
    }

    buffer[n] = '\0';
    cout << "receive from server: "<< buffer<< endl;

    close(sockfd);
    return 0;
}