C语言库函数(G类字母)-5

　　函数名: gety
功能: 返回当前图形位置的y坐标
用法: int far gety(void);
程序例:

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

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

/* move to the screen center point */
moveto(getmaxx() / 2, getmaxy() / 2);

/* create a message string */
sprintf(msg, "<-(%d, %d) is the here.", getx(), gety());

/* display the message */
outtext(msg);

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

函数名: gmtime
功能: 把日期和时间转换为格林尼治标准时间(GMT)
用法: strUCt tm *gmtime(long *clock);
程序例:

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <dos.h>

/* Pacific Standard Time & Daylight Savings */
char *tzstr = "TZ=PST8PDT";

int main(void)
{
time_t t;
struct tm *gmt, *area;

putenv(tzstr);
tzset();

t = time(NULL);
area = localtime(&t);
printf("Local time is: %s", asctime(area));
gmt = gmtime(&t);
printf("GMT is: %s", asctime(gmt));
return 0;
}

函数名: gotoxy
功能: 在文本窗口中设置光标
用法: void gotoxy(int x, int y);
程序例:

#include <conio.h>

int main(void)
{
clrscr();
gotoxy(35, 12);
cprintf("Hello world");
getch();
return 0;
}

函数名: gotoxy
功能: 在文本窗口中设置光标
用法: void gotoxy(int x, int y);
程序例:

#include <conio.h>

int main(void)
{
clrscr();
gotoxy(35, 12);
cprintf("Hello world");
getch();
return 0;
}

函数名: graphdefaults
功能: 将所有图形设置复位为它们的缺省值
用法: void far graphdefaults(void);
程序例:

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

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

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "c:\\bor\\Borland\\bgi");

/* 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 */
}

maxx = getmaxx();
maxy = getmaxy();

/* output line with non-default settings */
setlinestyle(DOTTED_LINE, 0, 3);
line(0, 0, maxx, maxy);
outtextxy(maxx/2, maxy/3, "Before default values are restored.");
getch();

/* restore default values for everything */
graphdefaults();

/* clear the screen */
cleardevice();

/* output line with default settings */
line(0, 0, maxx, maxy);
outtextxy(maxx/2, maxy/3, "After restoring default values.");

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

函数名: grapherrormsg
功能: 返回一个错误信息串的指针
用法: char *far grapherrormsg(int errorcode);
程序例:

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

#define NONSENSE -50

int main(void)
{
/* FORCE AN ERROR TO OCCUR */
int gdriver = NONSENSE, gmode, errorcode;

/* initialize graphics mode */
initgraph(&gdriver, &gmode, "");

/* read result of initialization */
errorcode = graphresult();

/* if an error occurred, then output a */
/* descriptive error message. */
if (errorcode != grOk)
{
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: 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 <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

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

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);
}