gethostbyname

最新推荐文章于 2024-12-05 11:43:25 发布

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本文通过C++代码示例介绍了如何使用socket编程中的gethostbyname和gethostbyaddr函数来实现域名到IP地址的转换及反向查询，并展示了具体的运行结果。

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#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <iostream>
#include <string.h>
#include <errno.h>


using namespace std;

int main(int argc, char *argv [])
{
	char sz [] = "Hello, World!";	//Hover mouse over "sz" while debugging to see its contents
	cout << sz << endl;	//<================= Put a breakpoint here
	
	struct hostent *host=NULL;
	char hostname [] = "www.163.com";
	struct sockaddr_in addr_in;
	char szText[32] = {0};
	extern int h_errno;
	
	if ((host = gethostbyname(hostname)) != NULL)
	{
		memcpy(&addr_in.sin_addr.s_addr, host->h_addr_list, 4);

		
		printf("Domain name:%s\n", hostname);
		printf("IP length: %d\n", host->h_length);
		printf("Type:%d\n", host->h_addrtype);
		printf("address: %s\n", inet_ntop(host->h_addrtype, host->h_addr, szText, sizeof(szText)));
		
		
	}
	else
	{
		char * mesg = strerror(errno);
		printf("%d\n", errno);
		printf("%s\n", mesg);
	}
	

	char addr [] = "220.162.97.209";
	host=gethostbyaddr(addr,sizeof(addr),AF_INET);
	if (host!=NULL)
	{
		memcpy(&addr_in.sin_addr.s_addr, host->h_addr_list, 4);
		printf("Domain name:%s\n", hostname);
		printf("IP length: %d\n", host->h_length);
		printf("Type:%d\n", host->h_addrtype);
		printf("address: %s\n", inet_ntop(host->h_addrtype, host->h_addr, szText, sizeof(szText)));
	}
	else
	{
		char * mesg = strerror(errno);
		printf("%d\n", errno);
		printf("%s\n", mesg);
	}

	
	
	return 0;
}

/*
Hello, World!
Domain name:www.163.com
IP length: 4
Type:2
address: 220.162.97.209
Domain name:www.163.com
IP length: 15
Type:2
address: 50.50.48.46

*/