C graphics.h Library

graphics.h is an old library that lets a C program open a drawing window and draw on it, like a starter art kit. You start it up, draw, and then close it.

In this page:

The graphics.h Header
initgraph and closegraph
getmaxx and getmaxy
cleardevice and Background Options
Modern Compatibility Details

Syntax

#include <graphics.h>

int gd = DETECT, gm;
initgraph(&gd, &gm, "");   // enter graphics mode
// ... drawing calls ...
getch();
closegraph();              // leave graphics mode

The graphics.h Header

The graphics.h header file acts as a gatekeeper to access over 70 unique drawing and utility functions. It maps your program coordinates directly to the video controller memory using BGI drivers.

Example: The graphics.h Header

#include <graphics.h>
int main() {
	initgraph(0, 0, "");
	circle(100, 100, 50);
	getch();
	closegraph();
	return 0;
}

initgraph and closegraph

The initgraph() function loads the graphics driver and puts the system into graphics mode. The closegraph() function shuts down the graphics system, freeing all allocated memory and loading back the text interface.

Example: initgraph and closegraph

#include <graphics.h>
// Program execution starts in main()
int main() {
	// Declare gd and set it to DETECT, gm
	int gd = DETECT, gm;
	initgraph(&gd, &gm, "");
	getch();
	closegraph();
	// Return 0 to signal that the program finished successfully
	return 0;
}

getmaxx and getmaxy

Screen sizes vary between platforms. Instead of hardcoding positions, use getmaxx() and getmaxy() to find the maximum resolution dynamically. This keeps your designs responsive.

Example: getmaxx and getmaxy

#include <graphics.h>
// Program execution starts in main()
int main() {
	initgraph(0, 0, "");
	// Declare centerX and set it to getmaxx() / 2
	int centerX = getmaxx() / 2;
	// Declare centerY and set it to getmaxy() / 2
	int centerY = getmaxy() / 2;
	putpixel(centerX, centerY, WHITE);
	getch();
	closegraph();
	// Return 0 to signal that the program finished successfully
	return 0;
}

cleardevice and Background Options

The cleardevice() function erases the current graphics screen, filling it with the background color. You can set the default background color using the setbkcolor() function.

Example: cleardevice and Background Options

#include <graphics.h>
int main() {
	initgraph(0, 0, "");
	setbkcolor(BLUE);
	cleardevice();
	getch();
	closegraph();
	return 0;
}

Modern Compatibility Details

Standard C compiler packages (like GCC on Windows or Linux) don't include graphics.h out of the box. Modern setups use custom BGI wrapper libraries, which use the same standard function signatures.

Example: Modern Compatibility Details

#include <graphics.h>
int main() {
	initgraph(0, 0, "");
	getch();
	closegraph();
	return 0;
}

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