20. FAQ o Win API

Q> How to learn what users is on mine (or not mine) the machine? 
A> 

#define STRICT 
#include <windows.h> 
#include <lm.h> 
#include <iostream.h> 
#include <tchar.h> 

void UserEnum () 
{ 
    BOOL keepGoing = TRUE; 
    DWORD entriesRead, totalEntries; 
    USER_INFO_2 * pInfo = NULL; 
    DWORD resumeHandle = 0;//must be 0 to start with 
    char nameBuf [UNLEN + 1];//constants defined in LMCONS.H 
    char commentBuf [MAXCOMMENTSZ + 1]; 
    WCHAR serverName [100]; 
    lstrcpyW (serverName, L "\\\\PDC");  
    while (keepGoing) 
    { 
        NET_API_STATUS ret = NetUserEnum ( 
            serverName,  
            2, 
            0, 
            (LPBYTE *) &pInfo,//Important: ADDRESS of POINTER 
	    sizeof (USER_INFO_2) * 100,//requested buffer size;  
            &entriesRead, 
            &totalEntries, 
            &resumeHandle); 

        keepGoing = (ret == ERROR_MORE_DATA); 

        if (ret == 0 || ret == ERROR_MORE_DATA) 
        { 
            DWORD i; 
            for (i = 0; i <entriesRead; i ++) 
            { 
                //Note that strings in the INFO structures 
                //will ALWAYS be Unicode, regardless of 
                //your settings! Even though they're declared 
                //as LPTSTR, they're always LPWSTR. 
                //I'm compiling for non-Unicode, so I 
                //convert them to ANSI strings... 
                //Check for NULL pointers in the INFO structure 
                LPWSTR pName = (LPWSTR) pInfo [i].usri2_name; 
                LPWSTR pComm = (LPWSTR) pInfo [i].usri2_comment; 
                if (pName == NULL) 
                { 
                    lstrcpy (nameBuf, "(no name!)"); 
                }
                else if (lstrlenW (pName) == 0) 
                { 
                    lstrcpy (nameBuf, "(empty name!)"); 
                }
                else 
                { 
                    WideCharToMultiByte (CP_OEMCP, 0, 
                        pName,-1, 
                        nameBuf, UNLEN, 
                        NULL, NULL); 
                }
                if (pComm == NULL) 
                { 
                    lstrcpy (commentBuf, "(no comment!)"); 
                }
                else if (lstrlenW (pComm) == 0) 
                { 
                    lstrcpy (commentBuf, "(empty comment!)"); 
                }
                else 
                { 
                    WideCharToMultiByte (CP_OEMCP, 0, 
                        pComm,-1, 
                        commentBuf, MAXCOMMENTSZ, 
                        NULL, NULL); 
                }
                cout <<nameBuf <<":" <<commentBuf <<endl; 
            }
        }
        else 
        { 
            cout <<"NetUserEnum error" <<ret <<endl; 
        }

        if (pInfo) 
        { 
            NetApiBufferFree (pInfo); 
            pInfo = NULL; 
        }
    }
}