给大家看看我的服务器代码：
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <time.h>

#define TIME_PORT 9090
#define DATA_SIZE 256

int main()
{
  int sock_fd;
  struct sockaddr_in local;
  struct sockaddr_in from;
  int fromlen,n;
  char buff[DATA_SIZE];
  time_t cur_time;
  sock_fd = socket(AF_INET,SOCK_DGRAM,0);
  if(sock_fd<0){
    printf("create socket error\n");
    return 0;
  }
  printf("create socket\n");

/*set ip and port*/
  local.sin_family=AF_INET;
  local.sin_port=htons(TIME_PORT);
  local.sin_addr.s_addr=INADDR_ANY;

/*set ip and port*/
  from.sin_family=AF_INET;
  from.sin_port=htons(TIME_PORT);
  from.sin_addr.s_addr=INADDR_ANY;
  fromlen = sizeof(from);
/*bind local to sock*/
  if(0!=bind(sock_fd,(struct sockaddr *)&local,sizeof(local))){
    printf("bind sock error\n");
    close(sock_fd);
    return 0;
  }
  printf("bind socket");
  
  fromlen =sizeof(from);
  printf("waiting request from client...\n");
  
  while(1)
  {
    n = recvfrom(sock_fd,buff,sizeof(buff),0,(struct sockaddr *)&from,&fromlen);
    if(n<=0){
      printf("RECV DATA ERROR\n");
      close(sock_fd);
      return 0;
    }
    buff[n]='\0';
    printf("client request: %s\n",buff);
    
    if(0==strncmp(buff,"quit",4)){
      break;
      }  
      if(0==strncmp(buff,"time",4)){
        int i;
      /*  cur_time = time(NULL);
        strcpy(buff,asctime(gmtime(&cur_time)))  ;
        *  printf("time:");
        for(i=0;i<DATA_SIZE||(*(buff+i)=='\0');i++){
          printf("%c",*(buff+i));
        }
          printf("\ntimeend\n");*/
strcpy(buff,"timezml");
printf("timeis: %s\n",buff);
      i=sendto(sock_fd,buff,sizeof(buff),0,(struct sockaddr *)&from,fromlen);
      if(i<0){
        printf("serv send errror\n");
        close(sock_fd);
        return 0;
      }else{
        printf("sendbyteis %d\n",i);
      }
      }
  }
  close(sock_fd);
  return 0;
}

最后sendto发送不了数据，执行结果“serv send errror”，一直找不到发送失败的原因，希望有人能帮忙解答。