how to run socket example C++?

Question

I am trying to run this socket C++ example from Microsoft it compile fine but when I click run it stop on first line // Validate the parameters and stop just want to ask did I miss something

#undef UNICODE

#include <winsock2.h>
#include <ws2tcpip.h>
#include <stdio.h>

// link with Ws2_32.lib
#pragma comment(lib, "Ws2_32.lib")

int __cdecl main(int argc, char **argv)
{

    //-----------------------------------------
    // Declare and initialize variables
    WSADATA wsaData;
    int iResult;
    INT iRetval;

    DWORD dwRetval;

    int i = 1;

    struct addrinfo *result = NULL;
    struct addrinfo *ptr = NULL;
    struct addrinfo hints;

    struct sockaddr_in  *sockaddr_ipv4;
    //    struct sockaddr_in6 *sockaddr_ipv6;
    LPSOCKADDR sockaddr_ip;

    char ipstringbuffer[46];
    DWORD ipbufferlength = 46;

    // Validate the parameters
    if (argc != 3) {
        printf("usage: %s <hostname> <servicename>\n", argv[0]);
        printf("       provides protocol-independent translation\n");
        printf("       from an ANSI host name to an IP address\n");
        printf("%s example usage\n", argv[0]);
        printf("   %s www.contoso.com 0\n", argv[0]);
        return 1;
    }

    // Initialize Winsock
    iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (iResult != 0) {
        printf("WSAStartup failed: %d\n", iResult);
        return 1;
    }

    //--------------------------------
    // Setup the hints address info structure
    // which is passed to the getaddrinfo() function
    ZeroMemory( &hints, sizeof(hints) );
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;

    printf("Calling getaddrinfo with following parameters:\n");
    printf("\tnodename = %s\n", argv[1]);
    printf("\tservname (or port) = %s\n\n", argv[2]);

    //--------------------------------
    // Call getaddrinfo(). If the call succeeds,
    // the result variable will hold a linked list
    // of addrinfo structures containing response
    // information
    dwRetval = getaddrinfo(argv[1], argv[2], &hints, &result);
    if ( dwRetval != 0 ) {
        printf("getaddrinfo failed with error: %d\n", dwRetval);
        WSACleanup();
        return 1;
    }

    printf("getaddrinfo returned success\n");

    // Retrieve each address and print out the hex bytes
    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;
        }
        printf("\tSocket type: ");
        switch (ptr->ai_socktype) {
        case 0:
            printf("Unspecified\n");
            break;
        case SOCK_STREAM:
            printf("SOCK_STREAM (stream)\n");
            break;
        case SOCK_DGRAM:
            printf("SOCK_DGRAM (datagram) \n");
            break;
        case SOCK_RAW:
            printf("SOCK_RAW (raw) \n");
            break;
        case SOCK_RDM:
            printf("SOCK_RDM (reliable message datagram)\n");
            break;
        case SOCK_SEQPACKET:
            printf("SOCK_SEQPACKET (pseudo-stream packet)\n");
            break;
        default:
            printf("Other %ld\n", ptr->ai_socktype);
            break;
        }
        printf("\tProtocol: ");
        switch (ptr->ai_protocol) {
        case 0:
            printf("Unspecified\n");
            break;
        case IPPROTO_TCP:
            printf("IPPROTO_TCP (TCP)\n");
            break;
        case IPPROTO_UDP:
            printf("IPPROTO_UDP (UDP) \n");
            break;
        default:
            printf("Other %ld\n", ptr->ai_protocol);
            break;
        }
        printf("\tLength of this sockaddr: %d\n", ptr->ai_addrlen);
        printf("\tCanonical name: %s\n", ptr->ai_canonname);
    }

    freeaddrinfo(result);
    WSACleanup();

    return 0;
}

Answer 1

if (argc != 3)

The program takes two command-line arguments: <hostname> <servicename>.

Either:

a) Run the program directly from the command-line (not in the debugger), and provide the arguments. E.g.

C:\somewhere\> sampleprogram.exe example.com 80

b) Edit your debugging options to start the program with some arguments.

1. Right-click the project in Visual Studio and select Properties.
2. Select the Debugging page (on the left side).
3. Edit the Command Arguments field.

Answer 2

if (argc != 3) {
        printf("usage: %s <hostname> <servicename>\n", argv[0]);
        printf("       provides protocol-independent translation\n");
        printf("       from an ANSI host name to an IP address\n");
        printf("%s example usage\n", argv[0]);
        printf("   %s www.contoso.com 0\n", argv[0]);
        return 1;
    }

argc counts the number of command-line arguments you gave your program. It will always be at least 1 (since your program is passed its name), but this program appears to need two more parameters. It looks like you need a hostname and a service name, as shown by the printfs.

This StackOverflow answer shows how to set command-line arguments for a program you're trying to debug.