swprintf具体怎么用啊

swprintf能读入double 型数据 可是不知道怎么用 哪位大神教教啊

http://zhidao.baidu.com/link?url=e5tsIjCLvStmRoGKbD_VlVm8QilYBlppQbmsS1nXlRbsbCafdeS_yr-4rqxseg0GDK3mAh7WOYvGYiKN1cAMkq

http://blog.csdn.net/andy511823558/article/details/17136865

TCHAR strR[256];
GetDlgItemText(hwnd, IDC_EDITR, strR, sizeof(strR));

int r = atoi(strR);
double dMJ = 3.1415926 * r * r; // 圆的面积

TCHAR strMJ[256];
swprintf(strMJ, L"%lf", dMJ);
SetDlgItemText(hwnd, IDC_EDITMJ, strMJ);