help with using structure

[softwareguy74]

hi,

I'm trying to use the gethostbyname() function from the winsock library.

A successful call to gethostbyname() will return a pointer to the HOSTENT structure.

So, I call it as follows:

HOSTENT Hostinfo;

Hostinfo = gethostbyname("www.yahoo.com");

But, it doesn't like that for some reason. The compiler error I get is:

"error C2679: binary '=' : no operator defined which takes a right-hand operand of type 'struct hostent *' (or there is no acceptable conversion)"

Am I calling it wrong? I have used structures before without a problem but this one seems to be giving me a problem..

Any ideas?

this might be your problem,

I took this out of MSDN

The application must never attempt to modify this structure or to free any of its components. Furthermore, only one copy of this structure is allocated per thread, so the application should copy any information it needs before issuing any other Windows Sockets function calls.

[Jop]

Here's a part from the API-Guide in VB, I think you'll be a ble to translate it (I'm not *yet* )

Public Function GetIPAddress() As String
    Dim sHostName As String * 256
    Dim lpHost As Long
    Dim HOST As HOSTENT
    Dim dwIPAddr As Long
    Dim tmpIPAddr() As Byte
    Dim I As Integer
    Dim sIPAddr As String
    If Not SocketsInitialize() Then
        GetIPAddress = ""
        Exit Function
    End If
    If gethostname(sHostName, 256) = SOCKET_ERROR Then
        GetIPAddress = ""
        MsgBox "Windows Sockets error " & Str$(WSAGetLastError()) & " has occurred. Unable to successfully get Host Name."
        SocketsCleanup
        Exit Function
    End If
    sHostName = Trim$(sHostName)
    lpHost = gethostbyname(sHostName)
    If lpHost = 0 Then
        GetIPAddress = ""
        MsgBox "Windows Sockets are not responding. " & "Unable to successfully get Host Name."
        SocketsCleanup
        Exit Function
    End If
    CopyMemoryIP HOST, lpHost, Len(HOST)
    CopyMemoryIP dwIPAddr, HOST.hAddrList, 4
    ReDim tmpIPAddr(1 To HOST.hLen)
    CopyMemoryIP tmpIPAddr(1), dwIPAddr, HOST.hLen
    For I = 1 To HOST.hLen
        sIPAddr = sIPAddr & tmpIPAddr(I) & "."
    Next
    GetIPAddress = Mid$(sIPAddr, 1, Len(sIPAddr) - 1)
    SocketsCleanup
End Function

[softwareguy74]

Okay,

In Visual Basic, it works fine. But in C++, when I try to save the return value of gethostbyname() to an int, it tells me:

cannot convert from 'struct hostent *' to 'int'

I called it as:

int pHost;
HOSTENT Host;

pHost = gethostbyname("www.yahoo.com);

I guess I need to do some sort of conversion from a struct to an int. How can this be acheived?

Thanks,

Dan

[Jop]

Well they declare it as long

Dim lpHost As Long
lpHost = gethostbyname(sHostName)

I don't know C++ very well, so good luck

[softwareguy74]

That's because a long in VB is the same as an int in C++...