Graphics Initialization

initgraph()

Syntax

void initgraph(int *graphdriver, int *graphmode, const char *pathtodriver);

Description

Initializes graphics mode, loads the driver, and prepares the display for drawing operations.

Parameters

• graphdriver: pointer to graphics driver variable.
• graphmode: pointer to graphics mode variable.
• pathtodriver: path to BGI drivers. In many modern/online setups, "" works.

In student programs, using DETECT with initgraph() is usually enough.

Example

#include <graphics.h>
#include <conio.h>

int main() {
    int gd = DETECT, gm;

    initgraph(&gd, &gm, "");
    circle(200, 200, 100);

    getch();
    closegraph();
    return 0;
}

detectgraph()

Syntax

void detectgraph(int *graphdriver, int *graphmode);

Detects driver and mode without initializing graphics. Useful if you want to inspect availability before calling initgraph().

int gd, gm;
detectgraph(&gd, &gm);
initgraph(&gd, &gm, "");

graphresult()

Syntax

int graphresult(void);

Returns status of the last graphics operation. You should check it after initgraph().

If return value is grOk, initialization succeeded.

grapherrormsg()

Syntax

char *grapherrormsg(int errorcode);

Converts a graphics error code into a readable message. Typically used with graphresult().

closegraph()

Syntax

void closegraph(void);

Shuts down graphics mode and restores text mode.

Always call closegraph() before program termination.

restorecrtmode()

Syntax

void restorecrtmode(void);

Restores text mode without fully closing graphics. Rare in beginner programs.

Typical Initialization Flow

1. Declare driver/mode variables.
2. Call initgraph().
3. Check graphresult().
4. Run drawing operations.
5. Wait for input.
6. Call closegraph().

Example with Error Handling

#include <graphics.h>
#include <conio.h>
#include <stdio.h>

int main() {
    int gd = DETECT, gm;

    initgraph(&gd, &gm, "");

    int errorcode = graphresult();
    if (errorcode != grOk) {
        printf("Graphics error: %s\n", grapherrormsg(errorcode));
        return 1;
    }

    circle(200, 200, 100);
    getch();
    closegraph();
    return 0;
}

Common Initialization Errors

• BGI driver not found.
• Incorrect BGI path in older Turbo C setups.
• Running graphics.h in unsupported compilers.
• Missing graphics drivers.
• Incorrect graphics mode selection.

Important reminders: graphics.h is not part of standard C, initialization must happen before drawing, and closegraph() must be called before exit.