/* clean up */
getch();
closegraph();
return 0;
}

函数名: graphresult
功 能: 返回最后一次不成功的图形操作的错误代码
用 法: int far graphresult(void);
程序例:

#include
#include
#include
#include

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;

/* 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 */
}

/* draw a line */
line(0, 0, getmaxx(), getmaxy());

/* clean up */
getch();
closegraph();
return 0;
}

函数名: _graphfreemem
功 能: 用户可修改的图形存储区释放函数
用 法: void far _graphfreemem(void far *ptr, unsigned size);
程序例:

#include
#include
#include
#include
#include

int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int midx, midy;

/* clear the text screen */
clrscr();
printf("Press any key to initialize graphics mode:");
getch();
clrscr();

/* 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;

/* display a message */
settextjustify(CENTER_TEXT, CENTER_TEXT);
outtextxy(midx, midy, "Press any key to exit graphics mode:");

/* clean up */
getch();
closegraph();
return 0;
}

/* called by the graphics kernel to allocate memory */
void far * far _graphgetmem(unsigned size)
{
printf("_graphgetmem called to allocate %d bytes.\n", size);
printf("hit any key:");
getch();
printf("\n");

/* allocate memory from far heap */
return farmalloc(size);
}

/* called by the graphics kernel to free memory */
void far _graphfreemem(void far *ptr, unsigned size)
{
printf("_graphfreemem called to free %d bytes.\n", size);
printf("hit any key:");
getch();
printf("\n");

/* free ptr from far heap */
farfree(ptr);
}

函数名: _graphgetmem
功 能: 用户可修改的图形存储区分配函数
用 法: void far *far _graphgetmem(unsigned size);
程序例:

#include
#include
#include
#include
#include

int main(void)
{
/* request autodetection */
int gdriver = DETECT, gmode, errorcode;
int midx, midy;

/* clear the text screen */
clrscr();
printf("Press any key to initialize graphics mode:");
getch();
clrscr();

/* 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;

/* display a message */
settextjustify(CENTER_TEXT, CENTER_TEXT);
outtextxy(midx, midy, "Press any key to exit graphics mode:");

/* clean up */
getch();
closegraph();
return 0;
}

/* called by the graphics kernel to allocate memory */
void far * far _graphgetmem(unsigned size)
{
printf("_graphgetmem called to allocate %d bytes.\n", size);
printf("hit any key:");
getch();
printf("\n");

/* allocate memory from far heap */
return farmalloc(size);
}

/* called by the graphics kernel to free memory */
void far _graphfreemem(void far *ptr, unsigned size)
{
printf("_graphfreemem called to free %d bytes.\n", size);
printf("hit any key:");
getch();
printf("\n");

/* free ptr from far heap */
farfree(ptr);
}