用visual c++6.0在屏幕上画圆，对圆的半径和坐标从键盘任意输入，然后再计算圆面积和在屏幕上画出相应的圆-With visual c++6.0 circle on the screen, on the radius and the coordinates of any input from the keyboard, and then calculate area of a circle and draw in the corr