scanf无法在多线程中工作

Question

我想创建一个多客户端处理服务器。它有1个线程来处理所有客户端，但scanf函数不工作，而while循环继续运行。

#include <stdio.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <string.h>
#include <pthread.h>
#define PORT 80
int totalclient = 0;
int clientsocket[100];

void error_message(char *m)
{
  printf("%s", m);
  exit(1);
}

void *multi_clients()
{
  int c1;

  while(1)
    printf("Server is running, enter your option for clients\n");
    scanf(" %d", &c1); // here scanf is not working.

  pthread_exit(NULL);
}

int main(void)
{
  pthread_t Thread;
  int sock, valread, valthread;
  struct sockaddr_in saddr;
  int addrlen = sizeof(saddr);
  int opt = 1;
  char buffer[] = "hello";
  int temp=0;

  if((sock = socket(AF_INET, SOCK_STREAM, 0)) == 0)
    error_message("socket cannot be created\n");

  if((setsockopt(sock, SOL_SOCKET, SO_REUSEADDR | SO_REUSEPORT,
        &opt, sizeof(opt))))
        error_message("setsocket");

  saddr.sin_family = AF_INET;
  saddr.sin_addr.s_addr = INADDR_ANY;
  saddr.sin_port = htons(PORT);

  if(bind(sock, (struct sockaddr *)&saddr, addrlen) <0)
    error_message("bind failed\n");

  if(listen(sock, 3) < 0)
    error_message("listen");

  if((valthread = pthread_create(&Thread, NULL, multi_clients,
                                  NULL)))
       error_message("thread\n");

  printf("accepting connection....\n");

  while(1)
  {
    if((clientsocket[totalclient] = accept(sock,
        (struct sockaddr *)&saddr, (socklen_t*)&addrlen)) <0)
        printf("error accepting connection\n");
    else
      send(clientsocket[totalclient], buffer, strlen(buffer), 0);
      totalclient++;
  }

  return 0;

}

是他们在多线程中从用户那里获取输入的任何其他更好的选择。