关于HWND hWndhWnd,HINSTANCE hInst;

HWND hWndhWnd,
hEditResult,
hButtonOptSum0,hButtonOptSum1,hButtonOptSum2,hButtonOptSum3,
hButtonOptSum4,hButtonOptSum5,hButtonOptSum6,hButtonOptSum7,
hButtonOptSum8,hButtonOptSum9,hButtonOptSumDec,
hButtonOptAdd,hButtonOptSub,hButtonOptMul,hButtonOptDiv,
hButtonOptSqrt,
hButtonOptPercent,hButtonOptEqu,
hButtonCancelEntry;
HINSTANCE hInst;
这是什么意思呀，我看不懂，是参数还是什么呀