函数名: line 
 功  能: 在指定两点间画一直线 
 用  法: #include <graphics.h> 
         void far line(int x0, int y0, int x1, int y1); 
 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 xmax, ymax; 
   /* initialize graphics and local variables */ 
    initgraph(&gdriver, &gmode, ""); 
   /* read result of initialization */ 
    errorcode = graphresult(); 
    /* an error occurred */ 
    if (errorcode != grOk) 
    { 
       printf("Graphics error: %s\n", 
              grapherrormsg(errorcode)); 
       printf("Press any key to halt:"); 
       getch(); 
       exit(1); 
    } 
   setcolor(getmaxcolor()); 
    xmax = getmaxx(); 
    ymax = getmaxy(); 
   /* draw a diagonal line */ 
    line(0, 0, xmax, ymax); 
   /* clean up */ 
    getch(); 
    closegraph(); 
    return 0; 
 }