C套接字编程没有输入端口

Question

我正在尝试为 C 套接字编程中未输入端口时设置默认端口号。有谁知道我该怎么做？我在尝试时不断遇到分段错误。

代码：

#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，但出现分段错误。如有任何帮助，我们将不胜感激！

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]));

C套接字编程没有输入端口

C socket programming no port entered

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connection

port

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