Thread: InetNtop undeclared identifier

  1. #1
    Registered User Vana Papi's Avatar
    Join Date
    Jul 2012

    InetNtop undeclared identifier

    I'm trying to launch the code from Beej's "Guide to Network Programming".
    I tried to google, but I didn't find a solution. Other people were able to fix SIMILAR problems with adding some header files or a lib, but it didn't work for me.
    The code looks like this(there are unnecessary headers, I know, but they are added just to rule out the possible header issue ) :
    #include <iostream>
    #include <winsock2.h>
    #include <windows.h>
    #include <Ws2tcpip.h>
    int main(int argc, char *argv[])
        WSADATA wsaData; // if this doesn't work
        //WSAData wsaData; // then try this instead
        // MAKEWORD(1,1) for Winsock 1.1, MAKEWORD(2,0) for Winsock 2.0:
        if (WSAStartup(MAKEWORD(1,1), &wsaData) != 0) {
        fprintf(stderr, "WSAStartup failed.\n");
    struct addrinfo hints, *res, *p;
    int status;
    char ipstr[INET6_ADDRSTRLEN];
    if (argc != 2) {
    fprintf(stderr,"usage: showip hostname\n");
    return 1;
    memset(&hints, 0, sizeof hints);
    hints.ai_family = AF_UNSPEC; // AF_INET or AF_INET6 to force version
    hints.ai_socktype = SOCK_STREAM;
    if ((status = getaddrinfo(argv[1], NULL, &hints, &res)) != 0) {
    fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(status));
    return 2;
    printf("IP addresses for %s:\n\n", argv[1]);
    for(p = res;p != NULL; p = p->ai_next) {
    void *addr;
    char *ipver;
    // get the pointer to the address itself,
    // different fields in IPv4 and IPv6:
    if (p->ai_family == AF_INET) { // IPv4
    struct sockaddr_in *ipv4 = (struct sockaddr_in *)p->ai_addr;
    addr = &(ipv4->sin_addr);
    ipver = "IPv4";
    } else { // IPv6
    struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)p->ai_addr;
    addr = &(ipv6->sin6_addr);
    ipver = "IPv6";
    // convert the IP to a string and print it:
    inet_ntop(p->ai_family, addr, ipstr, sizeof ipstr);
    printf(" %s: %s\n", ipver, ipstr);
    freeaddrinfo(res); // free the linked list
    return 0;
    Now I get inet_ntop undeclared(first use this in function).
    I've tried to replace it with inetNtop, and PCTSTR WSAAPI InetNtop. I still get the same thing.

    I've added 'libws2_32.a' and 'libsock32.a' under project->project options->parameters->add library or object in Dev-C++.

    I know the InetNtop should be avoided in the first place, but I'm trying to understand network programming before I start with the alternatives.

    Any idea whats wrong?

  2. #2
    Join Date
    Oct 2007
    Inside my computer
    Is your aim to write C or C++?
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

  3. #3
    Registered User Vana Papi's Avatar
    Join Date
    Jul 2012
    Quote Originally Posted by Elysia View Post
    Is your aim to write C or C++?
    Beej's guide and examples use C, but I aim to write c++.

    Are there alternative functions(except printf, which I can edit out in the first post).
    Last edited by Vana Papi; 08-01-2012 at 03:10 PM.

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