include<stdio.h>
include<graphics.h>
include <stdlib.h>
include <dos.h>
main()
int gd=DETECT,gm=0;
int i;
initgraph(&gd,&gm,"d:\tc");
cleardevice();
setcolor(11);
setlinestyle(SOLID_LINE,0,3);
for(i=50;i<=500;i=i+10)
rectangle(i,40,i+10,49);
rectangle(100,100,400,400) ;
}
上边框为什么是虚线????

朋友,那不是虚线,那是你自己画成那样的.你自己好好看看

for(i=50;i<=500;i=i+10)
rectangle(i,40,i+10,49);

这里你直接依次连续画了 45 个框,你看看

i = 50, -> rectangle(50, 40, 60, 49);
i = 60, -> rectangle(60, 40, 70, 49);
......

你看,这样这些框是连续紧挨的,所以你就觉得是虚线.