#include <graphics.h> void rectangle(int left, int top, int right, int bottom);
(left,top) is the upper left corner of the rectangle, and (right,bottom) is its lower right corner.
/* rectangle example */ #include <graphics.h> #include <stdlib.h> #include <stdio.h> #include <conio.h> int main(void) { /* request autodetection */ int gdriver = DETECT, gmode, errorcode; int left, top, right, bottom; /* 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(); exit(1); /* terminate with an error code */ } left = getmaxx() / 2 - 50; top = getmaxy() / 2 - 50; right = getmaxx() / 2 + 50; bottom = getmaxy() / 2 + 50; /* draw a rectangle */ rectangle(left,top,right,bottom); /* clean up */ getch(); closegraph(); return 0; }