struct hostent结构体使用

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结构体定义：

struct hostent{char *h_name;         //正式主机名char **h_aliases;     //主机别名int h_addrtype;       //主机IP地址类型：IPV4-AF_INETint h_length;  //主机IP地址字节长度，对于IPv4是四字节，即32位char **h_addr_list;  //主机的IP地址列表};#define h_addr h_addr_list[0]   //保存的是IP地址

实现例程：

#include <stdio.h>#include <netdb.h>#include <sys/socket.h>int main(int argc, char *argv[]){char *ptr, **pptr;struct hostent *hptr;char str[32] = {0};ptr = argv[1];if((hptr = gethostbyname(ptr)) == NULL){printf("gethostbyname error: %s\n", ptr);return 0;}printf("official hostname:%s\n", hptr->h_name);   //主机规范名for(pptr = hptr->h_aliases; *pptr != NULL; pptr++)   //将主机别名打印出来printf("alias: %s\n", *pptr);switch(hptr->h_addrtype)  //根据地址类型，将地址打印出来{case AF_INET:case AF_INET6:pptr = hptr->h_addr_list;for(; *pptr != NULL; pptr++)   //将得到的所有地址打印出来{printf("address: %s\n", inet_ntop(hptr->h_addrtype, *pptr, str, sizeof(str)));   //inet_ntop: 将网络字节序的二进制转换为文本字符串的格式printf("first address: %s\n", inet_ntop(hptr->h_addrtype, hptr->h_addr, str, sizeof(str)));}break;default:printf("unkown address type\n");break;}return 0;}

运行结果：

official hostname:www.a.shifen.com
alias: www.baidu.com
address: 115.239.211.112
first address: 115.239.211.112
address: 115.239.210.27
first address: 115.239.211.112

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