题目：画图，学用line画直线。
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程序源代码：
#include \main() {
int driver,mode,i; float x0,y0,y1,x1; float j=12,k;
driver=VGA;mode=VGAHI; initgraph(&driver,&mode,\setbkcolor(GREEN);
x0=263;y0=263;y1=275;x1=275; for(i=0;i<=18;i++) {
setcolor(5);
line(x0,y0,x0,y1); x0=x0-5; y0=y0-5; x1=x1+5; y1=y1+5; j=j+10; }
x0=263;y1=275;y0=263; for(i=0;i<=20;i++) {
setcolor(5);
line(x0,y0,x0,y1); x0=x0+5; y0=y0+5; y1=y1-5; } }
题目：画图，学用rectangle画方形。
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程序分析：利用for循环控制100-999个数，每个数分解出个位，十位，百位。
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程序源代码：
#include \main() {
int x0,y0,y1,x1,driver,mode,i; driver=VGA;mode=VGAHI; initgraph(&driver,&mode,\setbkcolor(YELLOW);
x0=263;y0=263;y1=275;x1=275; for(i=0;i<=18;i++) {
setcolor(1);
rectangle(x0,y0,x1,y1); x0=x0-5; y0=y0-5; x1=x1+5; y1=y1+5; }
settextstyle(DEFAULT_FONT,HORIZ_DIR,2); outtextxy(150,40,\line(130,60,480,60); setcolor(2);
circle(269,269,137); }
