C语言库函数举例说明（一） -- love_you

O字母开头

函数名: open
功能: 打开一个文件用于读或写
用法: int open(char *pathname, int access[, int permiss]);
程序例:
#include
#include
#include
#include

int main(void)
{
int handle;
char msg[] = "Hello world";

   if ((handle = open("TEST.$$$", O_CREAT | O_TEXT)) == -1)
   {
      perror("Error:");
      return 1;
   }
   write(handle, msg, strlen(msg));
   close(handle);
   return 0;
}

函数名: outport
功能: 输出整数到硬件端口中
用法: void outport(int port, int value);
程序例:

#include
#include

int main(void)
{
int value = 64;
int port = 0;

   outportb(port, value);
   printf("Value %d sent to port number %d\n", value, port);
   return 0;
}

函数名: outportb
功能: 输出字节到硬件端口中
用法: void outportb(int port, char byte);
程序例:

#include
#include

int main(void)
{
int value = 64;
int port = 0;

   outportb(port, value);
   printf("Value %d sent to port number %d\n", value, port);
   return 0;
}

函数名: outtext
功能: 在视区显示一个字符串
用法: void far outtext(char far *textstring);
程序例:

#include
#include
#include
#include

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

/* 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;

/* move the C.P. to the center of the screen */
moveto(midx, midy);

   /* output text starting at the C.P. */
   outtext("This ");
   outtext("is ");
   outtext("a ");
   outtext("test.");

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

函数名: outtextxy
功能: 在指定位置显示一字符串
用法: void far outtextxy(int x, int y, char *textstring);
程序例:

#include
#include
#include
#include

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

/* initialize graphics and local variables */
initgraph( &gdriver, &gmode, "");

midx = getmaxx() / 2;
midy = getmaxy() / 2;

   /* output text at the center of the screen*/
   /* Note: the C.P. doesn't get changed.*/
   outtextxy(midx, midy, "This is a test.");

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

P字母开头

函数名: parsfnm
功能: 分析文件名
用法: char *parsfnm (char *cmdline, struct fcb *fcbptr, int option);
程序例:

#include
#include
#include
#include

int main(void)
{
char line[80];
struct fcb blk;

   /* get file name */
   printf("Enter drive and file name (no path - ie. a:file.dat)\n");
   gets(line);

   /* put file name in fcb */
   if (parsfnm(line, &blk, 1) == NULL)
      printf("Error in parsfm call\n");
   else
      printf("Drive #%d Name: %11s\n", blk.fcb_drive, blk.fcb_name);

   return 0;
}

函数名: peek
功能: 检查存储单元
用法: int peek(int segment, unsigned offset);
程序例:

#include
#include
#include

int main(void)
{
int value = 0;

   printf("The current status of your keyboard is:\n");
   value = peek(0x0040, 0x0017);
   if (value & 1)
      printf("Right shift on\n");
   else
      printf("Right shift off\n");

   if (value & 2)
      printf("Left shift on\n");
   else
      printf("Left shift off\n");

   if (value & 4)
      printf("Control key on\n");
   else
      printf("Control key off\n");

   if (value & 8)
      printf("Alt key on\n");
   else
      printf("Alt key off\n");

   if (value & 16)
      printf("Scroll lock on\n");
   else
      printf("Scroll lock off\n");

   if (value & 32)
      printf("Num lock on\n");
   else
      printf("Num lock off\n");

   if (value & 64)
      printf("Caps lock on\n");
   else
      printf("Caps lock off\n");

   return 0;
}

函数名: peekb
功能: 检查存储单元
用法: char peekb (int segment, unsigned offset);
程序例:

#include
#include
#include

int main(void)
{
int value = 0;

   printf("The current status of your keyboard is:\n");
   value = peekb(0x0040, 0x0017);
   if (value & 1)
      printf("Right shift on\n");
   else
      printf("Right shift off\n");

   if (value & 2)
      printf("Left shift on\n");
   else
      printf("Left shift off\n");

   if (value & 4)
      printf("Control key on\n");
   else
      printf("Control key off\n");

   if (value & 8)
      printf("Alt key on\n");
   else
      printf("Alt key off\n");

   if (value & 16)
      printf("Scroll lock on\n");
   else
      printf("Scroll lock off\n");

   if (value & 32)
      printf("Num lock on\n");
   else
      printf("Num lock off\n");

   if (value & 64)
      printf("Caps lock on\n");
   else
      printf("Caps lock off\n");

   return 0;
}

函数名: perror
功能: 系统错误信息
用法: void perror(char *string);
程序例:

#include

int main(void)
{
FILE *fp;

   fp = fopen("perror.dat", "r");
   if (!fp)
      perror("Unable to open file for reading");
   return 0;
}

函数名: pieslice
功能: 绘制并填充一个扇形
用法: void far pieslice(int x, int stanle, int endangle, int radius);
程序例:

#include
#include
#include
#include

int main(void)
{
   /* request auto detection */
   int gdriver = DETECT, gmode, errorcode;
   int midx, midy;
   int stangle = 45, endangle = 135, radius = 100;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

midx = getmaxx() / 2;
midy = getmaxy() / 2;

   /* set fill style and draw a pie slice */
   setfillstyle(EMPTY_FILL, getmaxcolor());
   pieslice(midx, midy, stangle, endangle, radius);

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

函数名: poke
功能: 存值到一个给定存储单元
用法: void poke(int segment, int offset, int value);
程序例:

#include
#include

int main(void)
{
   clrscr();
   cprintf("Make sure the scroll lock key is off and press any key\r\n");
   getch();
   poke(0x0000,0x0417,16);
   cprintf("The scroll lock is now on\r\n");
   return 0;
}

函数名: pokeb
功能: 存值到一个给定存储单元
用法: void pokeb(int segment, int offset, char value);
程序例:

#include
#include

int main(void)
{
   clrscr();
   cprintf("Make sure the scroll lock key is off and press any key\r\n");
   getch();
   pokeb(0x0000,0x0417,16);
   cprintf("The scroll lock is now on\r\n");
   return 0;
}

函数名: poly
功能: 根据参数产生一个多项式
用法: double poly(double x, int n, double c[]);
程序例:

#include
#include

/* polynomial: x**3 - 2x**2 + 5x - 1 */

int main(void)
{
double array[] = { -1.0, 5.0, -2.0, 1.0 };
double result;

   result = poly(2.0, 3, array);
   printf("The polynomial: x**3 - 2.0x**2 + 5x - 1 at 2.0 is %lf\n",
           result);
   return 0;
}

函数名: pow
功能: 指数函数(x的y次方)
用法: double pow(double x, double y);
程序例:

#include
#include

int main(void)
{
double x = 2.0, y = 3.0;

   printf("%lf raised to %lf is %lf\n", x, y, pow(x, y));
   return 0;
}

函数名: pow10
功能: 指数函数(10的p次方)
用法: double pow10(int p);
程序例:

#include
#include

int main(void)
{
double p = 3.0;

   printf("Ten raised to %lf is %lf\n", p, pow10(p));
   return 0;
}

函数名: printf
功能: 产生格式化输出的函数
用法: int printf(char *format...);
程序例:

#include
#include

#define I 555
#define R 5.5

int main(void)
{
   int i,j,k,l;
   char buf[7];
   char *prefix = buf;
   char tp[20];
   printf("prefix 6d      6o      8x        10.2e        "
          "10.2f\n");
   strcpy(prefix,"%");
   for (i = 0; i < 2; i++)
   {
      for (j = 0; j < 2; j++)
         for (k = 0; k < 2; k++)
     for (l = 0; l < 2; l++)
            {
               if (i==0) strcat(prefix,"-");
               if (j==0) strcat(prefix,"+");
               if (k==0) strcat(prefix,"#");
               if (l==0) strcat(prefix,"0");
               printf("%5s |",prefix);
               strcpy(tp,prefix);
               strcat(tp,"6d |");
               printf(tp,I);
               strcpy(tp,"");
               strcpy(tp,prefix);
               strcat(tp,"6o |");
               printf(tp,I);
               strcpy(tp,"");
               strcpy(tp,prefix);
               strcat(tp,"8x |");
               printf(tp,I);
               strcpy(tp,"");
               strcpy(tp,prefix);
        strcat(tp,"10.2e |");
        printf(tp,R);
        strcpy(tp,prefix);
        strcat(tp,"10.2f |");
        printf(tp,R);
        printf(" \n");
        strcpy(prefix,"%");
     }
       }
   return 0;
}

函数名: putc
功能: 输出一字符到指定流中
用法: int putc(int ch, FILE *stream);
程序例:

#include

int main(void)
{
char msg[] = "Hello world\n";
int i = 0;

   while (msg[i])
      putc(msg[i++], stdout);
   return 0;
}

函数名: putch
功能: 输出字符到控制台
用法: int putch(int ch);
程序例:

#include
#include

int main(void)
{
char ch = 0;

   printf("Input a string:");
   while ((ch != '\r'))
   {
      ch = getch();
      putch(ch);
   }
   return 0;
}

函数名: putchar
功能: 在stdout上输出字符
用法: int putchar(int ch);
程序例:

#include

/* define some box-drawing characters */
#define LEFT_TOP 0xDA
#define RIGHT_TOP 0xBF
#define HORIZ 0xC4
#define VERT 0xB3
#define LEFT_BOT 0xC0
#define RIGHT_BOT 0xD9

int main(void)
{
char i, j;

   /* draw the top of the box */
   putchar(LEFT_TOP);
   for (i=0; i<10; i++)
      putchar(HORIZ);
   putchar(RIGHT_TOP);
   putchar('\n');

   /* draw the middle */
   for (i=0; i<4; i++)
   {
      putchar(VERT);
      for (j=0; j<10; j++)
         putchar(' ');
      putchar(VERT);
      putchar('\n');
   }

   /* draw the bottom */
   putchar(LEFT_BOT);
   for (i=0; i<10; i++)
      putchar(HORIZ);
   putchar(RIGHT_BOT);
   putchar('\n');

   return 0;
}

函数名: putenv
功能: 把字符串加到当前环境中
用法: int putenv(char *envvar);
程序例:

#include
#include
#include
#include
#include

int main(void)
{
char *path, *ptr;
int i = 0;

/* get the current path environment */
ptr = getenv("PATH");

   /* set up new path */
   path = malloc(strlen(ptr)+15);
   strcpy(path,"PATH=");
   strcat(path,ptr);
   strcat(path,";c:\\temp");

   /* replace the current path and display current environment */
   putenv(path);
   while (environ[i])
       printf("%s\n",environ[i++]);

   return 0;
}

函数名: putimage
功能: 在屏幕上输出一个位图
用法: void far putimage(int x, int y, void far *bitmap, int op);
程序例:

#include
#include
#include
#include

#define ARROW_SIZE 10

void draw_arrow(int x, int y);

int main(void)
{
   /* request autodetection */
   int gdriver = DETECT, gmode, errorcode;
   void *arrow;
   int x, y, maxx;
   unsigned int size;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

   maxx = getmaxx();
   x = 0;
   y = getmaxy() / 2;

/* draw the image to be grabbed */
draw_arrow(x, y);

/* calculate the size of the image */
size = imagesize(x, y-ARROW_SIZE, x+(4*ARROW_SIZE), y+ARROW_SIZE);

/* allocate memory to hold the image */
arrow = malloc(size);

/* grab the image */
getimage(x, y-ARROW_SIZE, x+(4*ARROW_SIZE), y+ARROW_SIZE, arrow);

   /* repeat until a key is pressed */
   while (!kbhit())
   {
      /* erase old image */
      putimage(x, y-ARROW_SIZE, arrow, XOR_PUT);

      x += ARROW_SIZE;
      if (x >= maxx)
          x = 0;

      /* plot new image */
      putimage(x, y-ARROW_SIZE, arrow, XOR_PUT);
   }

   /* clean up */
   free(arrow);
   closegraph();
   return 0;
}

void draw_arrow(int x, int y)
{
   /* draw an arrow on the screen */
   moveto(x, y);
   linerel(4*ARROW_SIZE, 0);
   linerel(-2*ARROW_SIZE, -1*ARROW_SIZE);
   linerel(0, 2*ARROW_SIZE);
   linerel(2*ARROW_SIZE, -1*ARROW_SIZE);
}

函数名: putpixel
功能: 在指定位置画一像素
用法: void far putpixel (int x, int y, int pixelcolor);
程序例:

#include
#include
#include
#include
#include

#define PIXEL_COUNT 1000
#define DELAY_TIME 100 /* in milliseconds */

int main(void)
{
   /* request autodetection */
   int gdriver = DETECT, gmode, errorcode;
   int i, x, y, color, maxx, maxy, maxcolor, seed;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

   maxx = getmaxx() + 1;
   maxy = getmaxy() + 1;
   maxcolor = getmaxcolor() + 1;

   while (!kbhit())
   {
      /* seed the random number generator */
      seed = random(32767);
      srand(seed);
      for (i=0; i      {
x = random(maxx);
         y = random(maxy);
         color = random(maxcolor);
         putpixel(x, y, color);
      }

      delay(DELAY_TIME);
      srand(seed);
      for (i=0; i      {
x = random(maxx);
y = random(maxy);
color = random(maxcolor);
if (color == getpixel(x, y))
     putpixel(x, y, 0);
      }
   }

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

函数名: puts
功能: 送一字符串到流中
用法: int puts(char *string);
程序例:

#include
int main(void)
{
char string[] = "This is an example output string\n";

   puts(string);
   return 0;
}

函数名: puttext
功能: 将文本从存储区拷贝到屏幕
用法: int puttext(int left, int top, int right, int bottom, void *source);
程序例:

#include
int main(void)
{
char buffer[512];

   /* put some text to the console */
   clrscr();
   gotoxy(20, 12);
   cprintf("This is a test. Press any key to continue ...");
   getch();

   /* grab screen contents */
   gettext(20, 12, 36, 21,buffer);
   clrscr();

   /* put selected characters back to the screen */
   gotoxy(20, 12);
   puttext(20, 12, 36, 21, buffer);
   getch();

   return 0;
}

函数名: putw
功能: 把一字符或字送到流中
用法: int putw(int w, FILE *stream);
程序例:

#include
#include

#define FNAME "test.$$$"

int main(void)
{
FILE *fp;
int word;

   /* place the word in a file */
   fp = fopen(FNAME, "wb");
   if (fp == NULL)
   {
      printf("Error opening file %s\n", FNAME);
      exit(1);
   }

   word = 94;
   putw(word,fp);
   if (ferror(fp))
       printf("Error writing to file\n");
   else
       printf("Successful write\n");
   fclose(fp);

   /* reopen the file */
   fp = fopen(FNAME, "rb");
   if (fp == NULL)
   {
      printf("Error opening file %s\n", FNAME);
      exit(1);
   }

   /* extract the word */
   word = getw(fp);
   if (ferror(fp))
       printf("Error reading file\n");
   else
       printf("Successful read: word = %d\n", word);

   /* clean up */
   fclose(fp);
   unlink(FNAME);

return 0;
}

Q字母开头

函数名: qsort
功能: 使用快速排序例程进行排序
用法: void qsort(void *base, int nelem, int width, int (*fcmp)());
程序例:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int sort_function( const void *a, const void *b);

char list[5][4] = { "cat", "car", "cab", "cap", "can" };

int main(void)
{
int x;

   qsort((void *)list, 5, sizeof(list[0]), sort_function);
   for (x = 0; x < 5; x++)
      printf("%s\n", list[x]);
   return 0;
}

int sort_function( const void *a, const void *b)
{
return( strcmp(a,b) );
}

R字母开头

函数名: raise
功能: 向正在执行的程序发送一个信号
用法: int raise(int sig);
程序例:

#include

int main(void)
{
int a, b;

   a = 10;
   b = 0;
   if (b == 0)
   /* preempt divide by zero error */
      raise(SIGFPE);
   a = a / b;
   return 0;
}

函数名: rand
功能: 随机数发生器
用法: void rand(void);
程序例:

#include
#include

int main(void)
{
int i;

   printf("Ten random numbers from 0 to 99\n\n");
   for(i=0; i<10; i++)
      printf("%d\n", rand() % 100);
   return 0;
}

函数名: randbrd
功能: 随机块读
用法: int randbrd(struct fcb *fcbptr, int reccnt);
程序例:

#include
#include
#include
#include

int main(void)
{
   char far *save_dta;
   char line[80], buffer[256];
   struct fcb blk;
   int i, result;

   /* get user input file name for dta */
   printf("Enter drive and file name (no path - i.e. a:file.dat)\n");
   gets(line);

   /* put file name in fcb */
   if (!parsfnm(line, &blk, 1))
   {
      printf("Error in call to parsfnm\n");
      exit(1);
   }
   printf("Drive #%d File: %s\n\n", blk.fcb_drive, blk.fcb_name);

/* open file with DOS FCB open file */
bdosptr(0x0F, &blk, 0);

   /* save old dta, and set new one */
   save_dta = getdta();
   setdta(buffer);

   /* set up info for the new dta */
   blk.fcb_recsize = 128;
   blk.fcb_random = 0L;
   result = randbrd(&blk, 1);

   /* check results from randbrd */
   if (!result)
      printf("Read OK\n\n");
   else
   {
      perror("Error during read");
      exit(1);
   }

   /* read in data from the new dta */
   printf("The first 128 characters are:\n");
   for (i=0; i<128; i++)
      putchar(buffer[i]);

/* restore previous dta */
setdta(save_dta);

return 0;
}

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\n");
   gets(line);

   /* parse the new file name to the dta */
   parsfnm(line,&blk,1);
   printf("Drive #%d File: %s\n", 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\n");
   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;
}

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\n", random (100));
   return 0;
}

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\n\n");
   for(i=0; i<10; i++)
       printf("%d\n", rand() % 100);
   return 0;
}

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\n");
      exit(1);
   }

   if ((bytes = read(handle, buf, 10)) == -1) {
      printf("Read Failed.\n");
      exit(1);
   }
   else {
      printf("Read: %d bytes read.\n", bytes);
   }
   return 0;
}

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\n Address is %p\n", str, str);
   str = realloc(str, 20);
   printf("String is %s\n New address is %p\n", str, str);

/* free memory */
free(str);

   return 0;
}

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, "");

   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;
}

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\n", grapherrormsg(errorcode));
      printf("Press any key to halt:");
      getch();
      exit(1); /* terminate with an error code */
   }

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

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

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

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.\n",file);
   else
      perror("remove");

   return 0;
}

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.\n", oldname, newname);
   else
      perror("rename");

   return 0;
}

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, "");

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're now in text mode.\n");
   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're back in graphics mode.");
   outtextxy(x, y+textheight("W"), "Press any key to halt:");

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

函数名: rewind
功能: 将文件指针重新指向一个流的开头
用法: int rewind(FILE *stream);
程序例:

#include
#include

int main(void)
{
FILE *fp;
char *fname = "TXXXXXX", *newname, first;

    newname = mktemp(fname);
    fp = fopen(newname,"w+");
    fprintf(fp,"abcdefghijklmnopqrstuvwxyz");
    rewind(fp);
    fscanf(fp,"%c",&first);
    printf("The first character is: %c\n",first);
    fclose(fp);
    remove(newname);

    return 0;
}

函数名: rmdir
功能: 删除DOS文件目录
用法: int rmdir(char *stream);
程序例:

#include
#include
#include
#include

#define DIRNAME "testdir.$$$"

int main(void)
{
int stat;

   stat = mkdir(DIRNAME);
   if (!stat)
          printf("Directory created\n");
   else
   {
      printf("Unable to create directory\n");
      exit(1);
   }

   getch();
   system("dir/p");
   getch();

   stat = rmdir(DIRNAME);
   if (!stat)
          printf("\nDirectory deleted\n");
   else
   {
   perror("\nUnable to delete directory\n");
      exit(1);
   }

return 0;
}

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C语言库函数举例说明（一）2006-01-24 14:28:00

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