题目：画图，综合例子2。（在TC中实现）。

程序分析：无。

程序源代码：

#include "graphics.h"
#define LEFT 0
#define TOP 0
#define RIGHT 639
#define BOTTOM 479
#define LINES 400
#define MAXCOLOR 15
int main()
{
    int driver,mode,error;
    int x1,y1;
    int x2,y2;
    int dx1,dy1,dx2,dy2,i=1;
    int count=0;
    int color=0;
    driver=VGA;
    mode=VGAHI;
    initgraph(&driver,&mode,"");
    x1=x2=y1=y2=10;
    dx1=dy1=2;
    dx2=dy2=3;
    while(!kbhit())
    {
        line(x1,y1,x2,y2);
        x1+=dx1;y1+=dy1;
        x2+=dx2;y2+dy2;
        if(x1<=LEFT||x1>=RIGHT)
            dx1=-dx1;
        if(y1<=TOP||y1>=BOTTOM)
            dy1=-dy1;
        if(x2<=LEFT||x2>=RIGHT)
            dx2=-dx2;
        if(y2<=TOP||y2>=BOTTOM)
                dy2=-dy2;
        if(++count>LINES)
        {
            setcolor(color);
            color=(color>=MAXCOLOR)?0:++color;
        }
    }
    closegraph();
}