Question

如果在 Visual C ++中提供URL，我如何解析主机IP地址？

Answer 1

我不确定是否有特定的C ++类来进行主机名查找，但是你总是可以使用普通的C来做这些事情。这是我在Linux，Mac OS X和Windows上编译和运行的版本。


#include <stdio.h>

#ifdef _WIN32
#  include "winsock.h"
#else
#  include <netdb.h>
#  include <arpa/inet.h>
#endif

static void initialise(void)
{
#ifdef _WIN32
    WSADATA data;
    if (WSAStartup (MAKEWORD(1, 1), &data) != 0)
    {
        fputs ("Could not initialise Winsock.\n", stderr);
        exit (1);
    }
#endif
}

static void uninitialise (void)
{
#ifdef _WIN32
    WSACleanup ();
#endif
}

int main (int argc, char *argv[])
{
    struct hostent *he;

    if (argc == 1)
        return -1;

    initialise();

    he = gethostbyname (argv[1]);
    if (he == NULL)
    {
        switch (h_errno)
        {
            case HOST_NOT_FOUND:
                fputs ("The host was not found.\n", stderr);
                break;
            case NO_ADDRESS:
                fputs ("The name is valid but it has no address.\n", stderr);
                break;
            case NO_RECOVERY:
                fputs ("A non-recoverable name server error occurred.\n", stderr);
                break;
            case TRY_AGAIN:
                fputs ("The name server is temporarily unavailable.", stderr);
                break;
        }
    }
    else
    {
        puts (inet_ntoa (*((struct in_addr *) he->h_addr_list[0])));
    }

    uninitialise ();

    return he != NULL;
}

编译完成后，提供主机名作为参数：

$ ./a.out stackoverflow.com
69.59.196.211

Answer 2

要在Windows下使用套接字功能，您必须先调用WSAStartup，指定所需的Winsock版本（为了您的目的，1.1将正常工作）。然后，您可以调用gethostbyname来获取主机的地址。当你完成后，你应该调用WSACleanup。把它们放在一起，就会得到这样的结果：

#include <windows.h>
#include <winsock.h>
#include <iostream>
#include <iterator>
#include <exception>
#include <algorithm>
#include <iomanip>

class use_WSA { 
    WSADATA d; 
    WORD ver;
public:
    use_WSA() : ver(MAKEWORD(1,1)) { 
        if ((WSAStartup(ver, &d)!=0) || (ver != d.wVersion))
            throw(std::runtime_error("Error starting Winsock"));
    }
    ~use_WSA() { WSACleanup(); }    
};

int main(int argc, char **argv) {
    if ( argc < 2 ) {
        std::cerr << "Usage: resolve <hostname>";
        return EXIT_FAILURE;
    }

    try { 
        use_WSA x;

        hostent *h = gethostbyname(argv[1]);
        unsigned char *addr = reinterpret_cast<unsigned char *>(h->h_addr_list[0]);
        std::copy(addr, addr+4, std::ostream_iterator<unsigned int>(std::cout, "."));
    }
    catch (std::exception const &exc) {
        std::cerr << exc.what() << "\n";
        return EXIT_FAILURE;
    }

    return 0;
}

Answer 3

解析URL以获取主机名。然后在您的平台上调用gethostbyname或相应的API以获取IP地址。如果要解析HTTP标头，请查找HostName标头以确定主机名。

Answer 4

struct hostent *he;

if ((he = gethostbyname("localhost") == NULL) {
    // Handle error: Failed
}

IP地址将在he->h_addr。适用于Windows，Linux和最有可能的macos。

Answer 5

简单易用：

在 Linux

上

#include <stdio.h>
#include <netdb.h>
#include <arpa/inet.h>
int main()
{
struct hostent *he=gethostbyname("www.stackoverflow.com");
char *ip=inet_ntoa(*(struct in_addr*)he->h_addr_list[0]);
printf("%s",ip);
}

在 Windows

上

#include <stdio.h>
#include <winsock.h>
int main()
{
WSADATA wsaData;
WSAStartup(MAKEWORD(2,2),&wsaData);
struct hostent *he=gethostbyname("www.stackoverflow.com");
char *ip=inet_ntoa(*(struct in_addr*)he->h_addr_list[0]);
printf("%s",ip);
}

Win Source

Answer 6

gethostbyname？

C ++从URL解析主机IP地址

6 个答案: