项目需要从域名解析地址，但是编译的时候提示gethostbyname error,百度了一下，这才发现，原来用了N年的gethostbyname 已经是obsolete 的函数了，都标记成DEPRECATED 了，无论是windows 下还是linux 下都建议使用getaddrinfo 来替代它。很好的总结经验：

gethostbyname函数的原型如下：

[cpp]struct hostent* FAR gethostbyname(

_In_ const char *name

);[/cpp]

之前使用gethostbyname 很简单，类似这样：

[cpp]struct hostent *remoteHost;

struct in_addr addr;

if ( ( remoteHost = gethostbyname( hostname ) ) == NULL ){

xxxx;

}

else{

if (remoteHost->h_addrtype == AF_INET)

{

while (remoteHost->h_addr_list[i] != 0) {

addr.s_addr = *(u_long *) remoteHost->h_addr_list[i++];

printf("\tIP Address #%d: %s\n", i, inet_ntoa(addr));

}

}

}[/cpp]

现在得用getaddrinfo，其原型如下：

[cpp]int WSAAPI getaddrinfo(

_In_opt_ PCSTR pNodeName,

_In_opt_ PCSTR pServiceName,

_In_opt_ const ADDRINFOA *pHints,

_Out_ PADDRINFOA *ppResult

);[/cpp]

得这么用：

[cpp]struct addrinfo *result = NULL;

struct addrinfo *ptr = NULL;

struct addrinfo hints;

ZeroMemory( &hints, sizeof(hints) );

hints.ai_family = AF_UNSPEC;

hints.ai_socktype = SOCK_STREAM;

hints.ai_protocol = IPPROTO_TCP;

dwRetval = getaddrinfo(hostname, 0, &hints, &result);

if ( dwRetval != 0 ) {

xxxx;

}

else{

for(ptr=result; ptr != NULL ;ptr=ptr->ai_next) {

printf("getaddrinfo response %d\n", i++);

printf("\tFlags: 0x%x\n", ptr->ai_flags);

printf("\tFamily: ");

switch (ptr->ai_family) {

case AF_UNSPEC:

printf("Unspecified\n");

break;

case AF_INET:

printf("AF_INET (IPv4)\n");

sockaddr_ipv4 = (struct sockaddr_in *) ptr->ai_addr;

printf("\tIPv4 address %s\n",

inet_ntoa(sockaddr_ipv4->sin_addr) );

break;

case AF_INET6:

printf("AF_INET6 (IPv6)\n");

// the InetNtop function is available on Windows Vista and later

// sockaddr_ipv6 = (struct sockaddr_in6 *) ptr->ai_addr;

// printf("\tIPv6 address %s\n",

// InetNtop(AF_INET6, &sockaddr_ipv6->sin6_addr, ipstringbuffer, 46) );

// We use WSAAddressToString since it is supported on Windows XP and later

sockaddr_ip = (LPSOCKADDR) ptr->ai_addr;

// The buffer length is changed by each call to WSAAddresstoString

// So we need to set it for each iteration through the loop for safety

ipbufferlength = 46;

iRetval = WSAAddressToString(sockaddr_ip, (DWORD) ptr->ai_addrlen, NULL,

ipstringbuffer, &ipbufferlength );

if (iRetval)

printf("WSAAddressToString failed with %u\n", WSAGetLastError() );

else

printf("\tIPv6 address %s\n", ipstringbuffer);

break;

case AF_NETBIOS:

printf("AF_NETBIOS (NetBIOS)\n");

break;

default:

printf("Other %ld\n", ptr->ai_family);

break;

}

}[/cpp]

转载自：mosir.org