#include <graphics.h>
int getmaxx(void);
 

getmaxx returns the maximum (screen-relative) x value for the current
graphics driver and mode.
For example, on a CGA in 320*200 mode, getmaxx returns 319. getmaxx is
invaluable for centering, determining the boundaries of a region
onscreen, and so on.

/* getmaxx example */
 
#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>
 
int main(void)
{
   /* request autodetection */
   int gdriver = DETECT, gmode, errorcode;
   int midx, midy;
   char xrange[80], yrange[80];
 
 
   /* 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 */
   }
 
   midx = getmaxx() / 2;
   midy = getmaxy() / 2;
 
   /* convert max resolution values to strings */
   sprintf(xrange, "X values range from 0..%d", getmaxx());
   sprintf(yrange, "Y values range from 0..%d", getmaxy());
 
   /* display the information */
   settextjustify(CENTER_TEXT, CENTER_TEXT);
   outtextxy(midx, midy, xrange);
   outtextxy(midx, midy + textheight("W"), yrange);
 
 
   /* clean up */
   getch();
   closegraph();
   return 0;
}

getmaxy getwindowwidth getx

  no output of example at the moment
  do not hesitate and add it...