How to get current username in C++?

Question

C++ / C#

I want to get the username of the current Windows session, but nothing happens.

char buffer[256]; // буфер
  DWORD size; // размер
  size = sizeof(buffer); // размер буфера
  GetUserName(buffer, &size);
  string userName = buffer;

It throws an error in line 4, like char buffer does not match the LPWSTR type.
Even though the book says so.

Answer 1

Windows indeed. In the headers, the function is defined like this:

BOOL WINAPI GetUserNameW(LPWSTR  lpBuffer, LPDWORD lpnSize);
BOOL WINAPI GetUserNameA(LPSTR  lpBuffer, LPDWORD lpnSize);
#ifdef _UNICODE
#define GetUserName GetUserNameW
#else
#define GetUserName GetUserNameA
#endif

Solutions to choose from:
And yes asd111 right, the buffer must be UNLEN+1 in size, otherwise a buffer overflow may occur, although this is unlikely.

Answer 2

#include <windows.h>
#include <Lmcons.h>

char username[UNLEN+1];
DWORD username_len = UNLEN+1;
GetUserName(username, &username_len);