用c语言实现线的绘制，可重复绘制，也可以设置参数对线的颜色等属性进行修改,这是最简单的c实现，其中的BGI必须先初始化，否则程序会报错-Using c language implementation line drawing, repeatable draw, you can also set the parameters on-line to modify the color and other attributes, it is the simplest c implementation, of which BGI must be initialized, otherwise program will complain