gethostbyname()

 /* * example of gethostbyname() * usage ./a.out www.qq.com */ #include<stdio.h> #include<unistd.h> #include<netdb.h> #include<sys/socket.h> #include<netinet/in.h> #include<arpa/inet.h> #include<stdlib.h> int main(int argc, char *argv[]) { struct hostent* hostName; struct in_addr hostAddr; if(argc!=2) { printf("usage:%s domain/n",argv[0]); exit(1); } hostName=gethostbyname(argv[1]); if (hostName==NULL) { perror("gethostbyname error/n"); exit(1); } hostAddr.s_addr=*((unsigned long* )hostName->h_addr_list[0]); printf("the host IP is %s/n",inet_ntoa(hostAddr)); return 0; }