错误信息如下
#gcc -o client.o client.c
/tmp/ccUGRzYU.o: In function ‘main’:
/tmp/ccUGRzYU.o(.text+0x45):undefined reference to ‘gethostbyname’
/tmp/ccUGRzYU.o(.text+0xda):uncefined reference to ‘socket’
/tmp/ccUGRzYU.o(.text+0x185):uncefined reference to ‘connect’
collect2: ld returned 1 exit status
源文件如下
/客户端程序 client.c**/
#include “stdio.h”
#include “stdlib.h”
#include “errno.h”
#include “sys/types.h”
#include “sys/socket.h”
#include “unistd.h”
#include “netinet/in.h”
#include “netdb.h”
int main(int argc, char *argv[])
{
int sockfd;
char buffer[1024];
struct sockaddr_in server_addr;
struct hostent *host;
int portnumber,nbytes;
if(argc!=3) {
fprintf(stderr,“Usage:%s hostname portnumber\a\n”,argv[0]);
exit(1);
}
if((host=gethostbyname(argv[1]))==NULL) {
fprintf(stderr,“Gethostname error\n”);
exit(1);
}
if((portnumber=atoi(argv[2]))<0) {
fprintf(stderr,“Usage:%s hostname portnumber\a\n”,argv[0]);
exit(1);
}
/客户程序开始建立 sockfd描述符/
if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1) {
fprintf(stderr,“Socket Error:%s\a\n”,strerror(errno));
exit(1);
}
/客户程序填充服务端的资料/
bzero(&server_addr,sizeof(server_addr));
server_addr.sin_family=AF_INET;
server_addr.sin_port=htons(portnumber);
server_addr.sin_addr=*((struct in_addr *)host->h_addr);
/客户程序发起连接请求/
if(connect(sockfd,(struct sockaddr *)(&server_addr),sizeof(struct sockaddr))==-1) {
fprintf(stderr,“Connect Error:%s\a\n”,strerror(errno));
exit(1);
}
if((nbytes=read(sockfd,buffer,1024))==-1) {
fprintf(stderr,“Read Error:%s\n”,strerror(errno));
exit(1);
}
buffer[nbytes]=’’;
printf(“I have received:%s\n”,buffer);
close(sockfd);
exit(0);
}