C套接字编程没有输入端口

Question

我正在尝试为C套接字编程中没有输入端口时设置默认端口号.有谁知道我怎么做到这一点？我一直在尝试分段错误.

码:

#define PORT 12345

int main(int argc, char *argv[]) {

    /* Thread and thread attributes */
    pthread_t client_thread;
    pthread_attr_t attr;


    int sockfd, new_fd;  /* listen on sock_fd, new connection on new_fd */
    struct sockaddr_in my_addr;    /* my address information */
    struct sockaddr_in their_addr; /* connector's address information */
    socklen_t sin_size;
    int i=0;

    /* Get port number for server to listen on */
    if (argc != 2) {
        fprintf(stderr,"usage: client port_number\n");
        exit(1);
    }

    /* generate the socket */
    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
        perror("socket");
        exit(1);
    }

    /* generate the end point */
    my_addr.sin_family = AF_INET;         
    my_addr.sin_port = htons(atoi(argv[1]));     
    my_addr.sin_addr.s_addr = INADDR_ANY; 

当argc!= 2时,我尝试将默认值设置为12345,但是我得到了分段错误.任何帮助,将不胜感激!

Answer 1

您可以使用条件表达式.

#define DEFAULT_PORT 12345
my_addr.sin_port = htons(argc < 2 ? DEFAULT_PORT : atoi(argv[1]));