符号引用错误。没有输出写入a.out

Question

#include <stdio.h>
#include<sys/socket.h>
#include <netinet/in.h>
#include <string.h>
int main()
{
  int welcomeSocket, newSocket;
  char buffer[1024];
  char str[1024];
  int len,k,i;
  struct sockaddr_in serverAddr;
  struct sockaddr_storage serverStorage;
  socklen_t addr_size;
  welcomeSocket= socket(PF_INET,SOCK_STREAM,0);

  serverAddr.sin_family=AF_INET;
  serverAddr.sin_port=htons(17100);
  serverAddr.sin_addr.s_addr=inet_addr("127.0.0.1");
  memset(serverAddr.sin_zero,'\0',sizeof serverAddr.sin_zero);

  bind (welcomeSocket, (struct sockaddr*)&serverAddr, sizeof(serverAddr));


  if(listen(welcomeSocket,5)==0)
        printf("Listening!\n");


  else
        printf("Error\n");


  addr_size= sizeof serverStorage;
  newSocket=accept(welcomeSocket,(struct 
  sockaddr*)&serverStorage,&addr_size);
  strcpy(buffer,"Enter string you want reversed or type exit: \n");
  send(newSocket,buffer,strlen(buffer),0);




  do
  {
        memset(buffer,0,strlen(buffer));
        recv(newSocket,buffer,1024,0);
        if(strcmp(buffer,"exit")==0)
                break;
        printf("%s\n",buffer);
        len=strlen(buffer);
        k=len-1;
        for(i=0;i<len;i++)
        {
                str[i]=buffer[k];            
                k--;
        }


        send(newSocket,str,strlen(str),0);
  }while(strcmp(buffer,"exit")!=0);


  return 0;
}

编译此代码时出现以下错误：
    gcc jason.c
    未定义的第一个引用的
    文件中的符号
    bind /tmp/cc9aqprX.o
    recv /tmp/cc9aqprX.o
    发送/tmp/cc9aqprX.o
    接受/tmp/cc9aqprX.o
    听/tmp/cc9aqprX.o
    socket /tmp/cc9aqprX.o
    inet_addr /tmp/cc9aqprX.o
    ld：致命：符号引用错误。没有输出写入a.out
    collect2：ld返回1退出状态

请帮助解决此问题？