linux sendto 源码

int sendto(int sockfd, const void *buf, size_t len, int flags,
           const struct sockaddr *dest_addr, socklen_t addrlen);

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>

int main() {
    int sockfd;
    struct sockaddr_in servaddr;

    // 创建 UDP 套接字
    if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
        perror("socket creation failed");
        exit(EXIT_FAILURE);
    }

    memset(&servaddr, 0, sizeof(servaddr));

    // Filling server information
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(8080);
    servaddr.sin_addr.s_addr = INADDR_ANY;

    char buffer[] = "Hello from client";
    int n = sendto(sockfd, (const char *)buffer, strlen(buffer),
                   MSG_CONFIRM, (const struct sockaddr *)&servaddr,
                   sizeof(servaddr));
    if (n < 0) {
        perror("sendto failed");
        exit(EXIT_FAILURE);
    }

    printf("Message sent successfully\n");

    close(sockfd);
    return 0;
}