如何用freemarker分割hashmap的值？(How to split a value of a hashmap with freemarker?)

 你有一些未成年人的问题和一些大问题： 
 
 小： 
 
 
 
 您不会在hints影响ai_protocol ，但当hints不为NULL时，它需要getaddrinfo() 
 
 
 您使用connect()的返回值作为文件描述符，但它是一个错误代码号。 您必须在客户端使用socket()返回的文件描述符，或者在服务器中使用accept() 。 
 
 
 在服务器中使用send()时，使用错误的文件描述符。 您不应该在处理SOCK_STREAM套接字类型的连接的文件描述符上发送数据。 
 
 
 getaddrinfo()返回一个列表，你应该迭代它，但是你认为总是有一个结果，但是它们可能是零或者多于一个。 
 
 
 hints被初始化，你用memset()调用未定义的行为，因为sizeof(struct addrinfo) > sizeof(struct addrinfo *)所以当你在ai上写0（GLOBAL ... GLOBAL EVERYWHERE） 
 
 
 大： 
 
 
 
 你没有理由地使用全局 
 
 
 您可以逐行声明多个变量。 
 
 
 你没有理由地使用全局 
 
 
 您不验证所有系统调用错误！ 
 
 
 你没有理由地使用全局 
 
 
 
// server and client
struct addrinfo hints = {
  .ai_family = AF_INET,
  .ai_socktype = SOCK_STREAM,
  .ai_flags = AI_PASSIVE,
  .ai_protocol = IPPROTO_TCP,
};
// server
if (send(connfd, &msg_s, 1, MSG_CONFIRM) == -1) {
  // error
}
// client
if (recv(sockfd, &msg_r, 1, MSG_CONFIRM) == -1) {
  // error
}

You have some minors issue and some big issue:
 
Small:
 
 
 
You don't affect ai_protocol in hints, but it's require by getaddrinfo() when hints is not NULL
 
 
You use the return of connect() as a file descriptor but it's a error code number. You must use the file descriptor return by socket() in a client, or by accept() in a server.
 
 
You use the wrong file descriptor when you use send() in the server. You SHOULD not send data on the file descriptor that handle connection in a SOCK_STREAM socket type.
 
 
getaddrinfo() return a list, you should iterate on it, but you assume that there is always one result, but they could be zero or more than one.
 
 
hints is initialized, you invoke undefined behavior with memset() because sizeof(struct addrinfo) > sizeof(struct addrinfo *) so you are out of bound when you write zero on ai (GLOBAL... GLOBAL EVERYWHERE)
 
 
Big:
 
 
 
You use global without reason
 
 
You declare more than one variable by line.
 
 
You use global without reason
 
 
You don't verify all your system call error !
 
 
You use global without reason
 
 
 
// server and client
struct addrinfo hints = {
  .ai_family = AF_INET,
  .ai_socktype = SOCK_STREAM,
  .ai_flags = AI_PASSIVE,
  .ai_protocol = IPPROTO_TCP,
};
// server
if (send(connfd, &msg_s, 1, MSG_CONFIRM) == -1) {
  // error
}
// client
if (recv(sockfd, &msg_r, 1, MSG_CONFIRM) == -1) {
  // error
}