GetAdaptersInfo and GetAdaptersAddressess BufferLength Param

Question

I\'ve got some legacy code in C++ here that does some things I don\'t understand. I\'m running it in Visual C++ 2008 Express Edition on a machine running Windows XP.

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Answer 1

Your code needs to look something like this:

// First get the desired size.
unsigned long outBufLen = 0;
DWORD dwResult = GetAdaptersInfo(NULL, &outBufLen);
if (dwResult == ERROR_BUFFER_OVERFLOW)  // This is what we're expecting
{
    // Now allocate a structure of the requried size.
    PIP_ADAPTER_INFO pIpAdapterInfo = (PIP_ADAPTER_INFO) malloc(outBufLen);
    dwResult = GetAdaptersInfo(pIpAdapterInfo, &outBufLen);
    if (dwResult == ERROR_SUCCESS)
    {
        // Yay!

Edit: See also Jeremy Friesner's answer for why this code isn't quite enough.