c语言函数大全

墙角野猫

函数名: randbwr
功 能: 随机块写
用 法: int randbwr(struct fcp *fcbptr, int reccnt);
程序例:
#include
#include
#include
#include
int main(void)
{
char far *save_dta;
char line[80];
char buffer[256] = "RANDBWR test!";
struct fcb blk;
int result;
/* get new file name from user */
printf("Enter a file name to create (no path - ie. a:file.dat
");
gets(line);
/* parse the new file name to the dta */
parsfnm(line,&blk,1);
printf("Drive #%d File: %s
", blk.fcb_drive, blk.fcb_name);
/* request DOS services to create file */
if (bdosptr(0x16, &blk, 0) == -1)
{
perror("Error creating file");
exit(1);
}
/* save old dta and set new dta */
save_dta = getdta();
setdta(buffer);
/* write new records */
blk.fcb_recsize = 256;
blk.fcb_random = 0L;
result = randbwr(&blk, 1);
if (!result)
printf("Write OK
");
else
{
perror("Disk error");
exit(1);
}
/* request DOS services to close the file */
if (bdosptr(0x10, &blk, 0) == -1)
{
perror("Error closing file");
exit(1);
}
/* reset the old dta */
setdta(save_dta);
return 0;
}

墙角野猫

函数名: random
功 能: 随机数发生器
用 法: int random(int num);
程序例:
#include
#include
#include
/* prints a random number in the range 0 to 99 */
int main(void)
{
randomize();
printf("Random number in the 0-99 range: %d
", random (100));
return 0;
}

墙角野猫

函数名: randomize
功 能: 初始化随机数发生器
用 法: void randomize(void);
程序例:
#include
#include
#include
int main(void)
{
int i;
randomize();
printf("Ten random numbers from 0 to 99
");
for(i=0; i<10; i++)
printf("%d
", rand() % 100);
return 0;
}

墙角野猫

函数名: read
功 能: 从文件中读
用 法: int read(int handle, void *buf, int nbyte);
程序例:
#include
#include
#include
#include
#include
#include
int main(void)
{
void *buf;
int handle, bytes;
buf = malloc(10);
/*
Looks for a file in the current directory named TEST.$$$ and attempts
to read 10 bytes from it. To use this example you should create the
file TEST.$$$
*/
if ((handle =
open("TEST.$$$", O_RDONLY | O_BINARY, S_IWRITE | S_IREAD)) == -1)
{
printf("Error Opening File
");
exit(1);
}
if ((bytes = read(handle, buf, 10)) == -1) {
printf("Read Failed.
");
exit(1);
}
else {
printf("Read: %d bytes read.
", bytes);
}
return 0;
}

墙角野猫

函数名: realloc
功 能: 重新分配主存
用 法: void *realloc(void *ptr, unsigned newsize);
程序例:
#include
#include
#include
int main(void)
{
char *str;
/* allocate memory for string */
str = malloc(10);
/* copy "Hello" into string */
strcpy(str, "Hello");
printf("String is %s
Address is %p
", str, str);
str = realloc(str, 20);
printf("String is %s
New address is %p
", str, str);
/* free memory */
free(str);
return 0;
}

墙角野猫

函数名: rectangle
功 能: 画一个矩形
用 法: void far rectangle(int left, int top, int right, int bottom);
程序例:
#include
#include
#include
#include
int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int left, top, right, bottom;
/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");
/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s
", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}
left = getmaxx() / 2 - 50;
top = getmaxy() / 2 - 50;
right = getmaxx() / 2 + 50;
bottom = getmaxy() / 2 + 50;
/* draw a rectangle */
rectangle(left,top,right,bottom);
/* clean up */
getch();
closegraph();
return 0;
}

墙角野猫

函数名: registerbgidriver
功 能: 登录已连接进来的图形驱动程序代码
用 法: int registerbgidriver(void(*driver)(void));
程序例:
#include
#include
#include
#include
int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
/* register a driver that was added into graphics.lib */
errorcode = registerbgidriver(EGAVGA_driver);
/* report any registration errors */
if (errorcode < 0)
{
printf("Graphics error: %s
", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}
/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");
/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s
", 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;
}

墙角野猫

函数名: remove
功 能: 删除一个文件
用 法: int remove(char *filename);
程序例:
#include
int main(void)
{
char file[80];
/* prompt for file name to delete */
printf("File to delete: ");
gets(file);
/* delete the file */
if (remove(file)== 0)
printf("Removed %s.
",file);
else
perror("remove");
return 0;
}

墙角野猫

函数名: rename
功 能: 重命名文件
用 法: int rename(char *oldname, char *newname);
程序例:
#include
int main(void)
{
char oldname[80], newname[80];
/* prompt for file to rename and new name */
printf("File to rename: ");
gets(oldname);
printf("New name: ");
gets(newname);
/* Rename the file */
if (rename(oldname, newname)== 0)
printf("Renamed %s to %s.
", oldname, newname);
else
perror("rename");
return 0;
}

墙角野猫

函数名: restorecrtmode
功 能: 将屏幕模式恢复为先前的imitgraph设置
用 法: void far restorecrtmode(void);
程序例:
#include
#include
#include
#include
int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int x, y;
/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");
/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %s
", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
}
x = getmaxx() / 2;
y = getmaxy() / 2;
/* output a message */
settextjustify(CENTER_TEXT, CENTER_TEXT);
outtextxy(x, y, "Press any key to exit graphics:");
getch();
/* restore system to text mode */
restorecrtmode();
printf("We&#39;re now in text mode.
");
printf("Press any key to return to graphics mode:");
getch();
/* return to graphics mode */
setgraphmode(getgraphmode());
/* output a message */
settextjustify(CENTER_TEXT, CENTER_TEXT);
outtextxy(x, y, "We&#39;re back in graphics mode.");
outtextxy(x, y+textheight("W"), "Press any key to halt:");
/* clean up */
getch();
closegraph();
return 0;
}