函数名: drawpoly 
 功  能: 画多边形 
 用  法: #include <graphics.h> 
         void far drawpoly(int numpoints, int far *polypoints); 
 程序例: 
#include <graphics.h> 
 #include <stdlib.h> 
 #include <stdio.h> 
 #include <conio.h> 
int main(void) 
 { 
    /* request auto detection */ 
    int gdriver = DETECT, gmode, errorcode; 
    int maxx, maxy; 
   /* our polygon array */ 
    int poly[10]; 
   /* initialize graphics and local 
       variables */ 
    initgraph(&gdriver, &gmode, ""); 
   /* read result of initialization */ 
    errorcode = graphresult(); 
    if (errorcode != grOk) 
    /* an error occurred */ 
    { 
       printf("Graphics error: %s\n", \ 
       grapherrormsg(errorcode)); 
       printf("Press any key to halt:"); 
       getch(); 
    /* terminate with an error code */ 
       exit(1); 
    } 
   maxx = getmaxx(); 
    maxy = getmaxy(); 
   poly[0] = 20;        /* 1st vertext */ 
    poly[1] = maxy / 2; 
   poly[2] = maxx - 20; /* 2nd */ 
    poly[3] = 20; 
   poly[4] = maxx - 50; /* 3rd */ 
    poly[5] = maxy - 20; 
   poly[6] = maxx / 2;  /* 4th */ 
    poly[7] = maxy / 2; 
 /* 
    drawpoly doesn't automatically close 
    the polygon, so we close it. 
 */ 
    poly[8] = poly[0]; 
    poly[9] = poly[1]; 
   /* draw the polygon */ 
    drawpoly(5, poly); 
   /* clean up */ 
    getch(); 
    closegraph(); 
    return 0; 
 }