站長(zhǎng)資訊網(wǎng)函數(shù)名: fabs
功 能: 返回浮點(diǎn)數(shù)的絕對(duì)值
用 法: double fabs(double x);
程序例:
#include <stdio.h>
#include <math.h>
int main(void)
{
float number = -1234.0;
printf(“number: %f absolute value: %fn”,
number, fabs(number));
return 0;
}
函數(shù)名: farcalloc
功 能: 從遠(yuǎn)堆棧中申請(qǐng)空間
用 法: void far *farcalloc(unsigned long units, unsigned ling unitsz);
程序例:
#include <stdio.h>
#include <alloc.h>
#include <string.h>
#include <dos.h>
int main(void)
{
char far *fptr;
char *str = “Hello”;
/* allocate memory for the far pointer */
fptr = farcalloc(10, sizeof(char));
/* copy “Hello” into allocated memory */
/*
Note: movedata is used because you
might be in a small data model, in
which case a normal string copy routine
can not be used since it assumes the
pointer size is near.
*/
movedata(FP_SEG(str), FP_OFF(str),
FP_SEG(fptr), FP_OFF(fptr),
strlen(str));
/* display string (note the F modifier) */
printf(“Far string is: %Fsn”, fptr);
/* free the memory */
farfree(fptr);
return 0;
}
函數(shù)名: farcoreleft
功 能: 返回遠(yuǎn)堆中未作用存儲(chǔ)區(qū)大小
用 法: long farcoreleft(void);
程序例:
#include <stdio.h>
#include <alloc.h>
int main(void)
{
printf(“The difference between the
highest allocated block in the
farn”);
printf(“heap and the top of the far heap
is: %lu bytesn”, farcoreleft());
return 0;
}
函數(shù)名: farfree
功 能: 從遠(yuǎn)堆中釋放一塊
用 法: void farfree(void);
程序例:
#include <stdio.h>
#include <alloc.h>
#include <string.h>
#include <dos.h>
int main(void)
{
char far *fptr;
char *str = “Hello”;
/* allocate memory for the far pointer */
fptr = farcalloc(10, sizeof(char));
/* copy “Hello” into allocated memory */
/*
Note: movedata is used because you might be in a small data model,
in which case a normal string copy routine can’t be used since it
assumes the pointer size is near.
*/
movedata(FP_SEG(str), FP_OFF(str),
FP_SEG(fptr), FP_OFF(fptr),
strlen(str));
/* display string (note the F modifier) */
printf(“Far string is: %Fsn”, fptr);
/* free the memory */
farfree(fptr);
return 0;
}
函數(shù)名: farmalloc
功 能: 從遠(yuǎn)堆中分配存儲(chǔ)塊
用 法: void far *farmalloc(unsigned long size);
程序例:
#include <stdio.h>
#include <alloc.h>
#include <string.h>
#include <dos.h>
int main(void)
{
char far *fptr;
char *str = “Hello”;
/* allocate memory for the far pointer */
fptr = farmalloc(10);
/* copy “Hello” into allocated memory */
/*
Note: movedata is used because we might
be in a small data model, in which case
a normal string copy routine can not be
used since it assumes the pointer size
is near.
*/
movedata(FP_SEG(str), FP_OFF(str),
FP_SEG(fptr), FP_OFF(fptr),
strlen(str));
/* display string (note the F modifier) */
printf(“Far string is: %Fsn”, fptr);
/* free the memory */
farfree(fptr);
return 0;
}
函數(shù)名: farrealloc
功 能: 調(diào)整遠(yuǎn)堆中的分配塊
用 法: void far *farrealloc(void far *block, unsigned long newsize);
程序例:
#include <stdio.h>
#include <alloc.h>
int main(void)
{
char far *fptr;
fptr = farmalloc(10);
printf(“First address: %Fpn”, fptr);
fptr = farrealloc(fptr,20);
printf(“New address : %Fpn”, fptr);
farfree(fptr);
return 0;
}
函數(shù)名: fclose
功 能: 關(guān)閉一個(gè)流
用 法: int fclose(FILE *stream);
程序例:
#include <string.h>
#include <stdio.h>
int main(void)
{
FILE *fp;
char buf[11] = “0123456789”;
/* create a file containing 10 bytes */
fp = fopen(“DUMMY.FIL”, “w”);
fwrite(&buf, strlen(buf), 1, fp);
/* close the file */
fclose(fp);
return 0;
}
函數(shù)名: fcloseall
功 能: 關(guān)閉打開(kāi)流
用 法: int fcloseall(void);
程序例:
#include <stdio.h>
int main(void)
{
int streams_closed;
/* open two streams */
fopen(“DUMMY.ONE”, “w”);
fopen(“DUMMY.TWO”, “w”);
/* close the open streams */
streams_closed = fcloseall();
if (streams_closed == EOF)
/* issue an error message */
perror(“Error”);
else
/* print result of fcloseall() function */
printf(“%d streams were closed.n”, streams_closed);
return 0;
}
函數(shù)名: fcvt
功 能: 把一個(gè)浮點(diǎn)數(shù)轉(zhuǎn)換為字符串
用 法: char *fcvt(double value, int ndigit, int *decpt, int *sign);
程序例:
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>
int main(void)
{
char *string;
double value;
int dec, sign;
int ndig = 10;
clrscr();
value = 9.876;
string = ecvt(value, ndig, &dec, &sign);
printf(“string = %s dec = %d
sign = %dn”, string, dec, sign);
value = -123.45;
ndig= 15;
string = ecvt(value,ndig,&dec,&sign);
printf(“string = %s dec = %d sign = %dn”,
string, dec, sign);
value = 0.6789e5; /* scientific
notation */
ndig = 5;
string = ecvt(value,ndig,&dec,&sign);
printf(“string = %s dec = %d
sign = %dn”, string, dec, sign);
return 0;
}
函數(shù)名: fdopen
功 能: 把流與一個(gè)文件句柄相接
用 法: FILE *fdopen(int handle, char *type);
程序例:
#include <sysstat.h>
#include <stdio.h>
#include <fcntl.h>
#include <io.h>
int main(void)
{
int handle;
FILE *stream;
/* open a file */
handle = open(“DUMMY.FIL”, O_CREAT,
S_IREAD | S_IWRITE);
/* now turn the handle into a stream */
stream = fdopen(handle, “w”);
if (stream == NULL)
printf(“fdopen failedn”);
else
{
fprintf(stream, “Hello worldn”);
fclose(stream);
}
return 0;
}
函數(shù)名: feof
功 能: 檢測(cè)流上的文件結(jié)束符
用 法: int feof(FILE *stream);
程序例:
#include <stdio.h>
int main(void)
{
FILE *stream;
/* open a file for reading */
stream = fopen(“DUMMY.FIL”, “r”);
/* read a character from the file */
fgetc(stream);
/* check for EOF */
if (feof(stream))
printf(“We have reached end-of-filen”);
/* close the file */
fclose(stream);
return 0;
}
函數(shù)名: ferror
功 能: 檢測(cè)流上的錯(cuò)誤
用 法: int ferror(FILE *stream);
程序例:
#include <stdio.h>
int main(void)
{
FILE *stream;
/* open a file for writing */
stream = fopen(“DUMMY.FIL”, “w”);
/* force an error condition by attempting to read */
(void) getc(stream);
if (ferror(stream)) /* test for an error on the stream */
{
/* display an error message */
printf(“Error reading from DUMMY.FILn”);
/* reset the error and EOF indicators */
clearerr(stream);
}
fclose(stream);
return 0;
}
函數(shù)名: fflush
功 能: 清除一個(gè)流
用 法: int fflush(FILE *stream);
程序例:
#include <string.h>
#include <stdio.h>
#include <conio.h>
#include <io.h>
void flush(FILE *stream);
int main(void)
{
FILE *stream;
char msg[] = “This is a test”;
/* create a file */
stream = fopen(“DUMMY.FIL”, “w”);
/* write some data to the file */
fwrite(msg, strlen(msg), 1, stream);
clrscr();
printf(“Press any key to flush
DUMMY.FIL:”);
getch();
/* flush the data to DUMMY.FIL without
closing it */
flush(stream);
printf(“nFile was flushed, Press any key
to quit:”);
getch();
return 0;
}
void flush(FILE *stream)
{
int duphandle;
/* flush the stream’s internal buffer */
fflush(stream);
/* make a duplicate file handle */
duphandle = dup(fileno(stream));
/* close the duplicate handle to flush
the DOS buffer */
close(duphandle);
}
函數(shù)名: fgetc
功 能: 從流中讀取字符
用 法: int fgetc(FILE *stream);
程序例:
#include <string.h>
#include <stdio.h>
#include <conio.h>
int main(void)
{
FILE *stream;
char string[] = “This is a test”;
char ch;
/* open a file for update */
stream = fopen(“DUMMY.FIL”, “w+”);
/* write a string into the file */
fwrite(string, strlen(string), 1, stream);
/* seek to the beginning of the file */
fseek(stream, 0, SEEK_SET);
do
{
/* read a char from the file */
ch = fgetc(stream);
/* display the character */
putch(ch);
} while (ch != EOF);
fclose(stream);
return 0;
}
函數(shù)名: fgetchar
功 能: 從流中讀取字符
用 法: int fgetchar(void);
程序例:
#include <stdio.h>
int main(void)
{
char ch;
/* prompt the user for input */
printf(“Enter a character followed by
<Enter>: “);
/* read the character from stdin */
ch = fgetchar();
/* display what was read */
printf(“The character read is: ‘%c’n”,
ch);
return 0;
}
函數(shù)名: fgetpos
功 能: 取得當(dāng)前文件的句柄
用 法: int fgetpos(FILE *stream);
程序例:
#include <string.h>
#include <stdio.h>
int main(void)
{
FILE *stream;
char string[] = “This is a test”;
fpos_t filepos;
/* open a file for update */
stream = fopen(“DUMMY.FIL”, “w+”);
/* write a string into the file */
fwrite(string, strlen(string), 1, stream);
/* report the file pointer position */
fgetpos(stream, &filepos);
printf(“The file pointer is at byte
%ldn”, filepos);
fclose(stream);
return 0;
}
函數(shù)名: fgets
功 能: 從流中讀取一字符串
用 法: char *fgets(char *string, int n, FILE *stream);
程序例:
#include <string.h>
#include <stdio.h>
int main(void)
{
FILE *stream;
char string[] = “This is a test”;
char msg[20];
/* open a file for update */
stream = fopen(“DUMMY.FIL”, “w+”);
/* write a string into the file */
fwrite(string, strlen(string), 1, stream);
/* seek to the start of the file */
fseek(stream, 0, SEEK_SET);
/* read a string from the file */
fgets(msg, strlen(string)+1, stream);
/* display the string */
printf(“%s”, msg);
fclose(stream);
return 0;
}
函數(shù)名: filelength
功 能: 取文件長(zhǎng)度字節(jié)數(shù)
用 法: long filelength(int handle);
程序例:
#include <string.h>
#include <stdio.h>
#include <fcntl.h>
#include <io.h>
int main(void)
{
int handle;
char buf[11] = “0123456789”;
/* create a file containing 10 bytes */
handle = open(“DUMMY.FIL”, O_CREAT);
write(handle, buf, strlen(buf));
/* display the size of the file */
printf(“file length in bytes: %ldn”,
filelength(handle));
/* close the file */
close(handle);
return 0;
}
函數(shù)名: fillellipse
功 能: 畫(huà)出并填充一橢圓
用 法: void far fillellipse(int x, int y, int xradius, int yradius);
程序例:
#include <graphics.h>
#include <conio.h>
int main(void)
{
int gdriver = DETECT, gmode;
int xcenter, ycenter, i;
initgraph(&gdriver,&gmode,””);
xcenter = getmaxx() / 2;
ycenter = getmaxy() / 2;
for (i=0; i<13; i++)
{
setfillstyle(i,WHITE);
fillellipse(xcenter,ycenter,100,50);
getch();
}
closegraph();
return 0;
}
函數(shù)名: fillpoly
功 能: 畫(huà)并填充一個(gè)多邊形
用 法: void far fillpoly(int numpoints, int far *polypoints);
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 i, maxx, maxy;
/* our polygon array */
int poly[8];
/* initialize graphics, local variables */
initgraph(&gdriver, &gmode, “”);
/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk)
/* an error occurred */
{
printf(“Graphics error: %sn”,
grapherrormsg(errorcode));
printf(“Press any key to halt:”);
getch();
exit(1);
/* terminate with an error code */
}
maxx = getmaxx();
maxy = getmaxy();
poly[0] = 20; /* 1st vertext */
poly[1] = maxy / 2;
poly[2] = maxx – 20; /* 2nd */
poly[3] = 20;
poly[4] = maxx – 50; /* 3rd */
poly[5] = maxy – 20;
/*
4th vertex. fillpoly automatically
closes the polygon.
*/
poly[6] = maxx / 2;
poly[7] = maxy / 2;
/* loop through the fill patterns */
for (i=EMPTY_FILL; i<USER_FILL; i++)
{
/* set fill pattern */
setfillstyle(i, getmaxcolor());
/* draw a filled polygon */
fillpoly(4, poly);
getch();
}
/* clean up */
closegraph();
return 0;
}
函數(shù)名: findfirst, findnext
功 能: 搜索磁盤(pán)目錄; 取得下一個(gè)匹配的findfirst模式的文件
用 法: int findfirst(char *pathname, struct ffblk *ffblk, int attrib);
int findnext(struct ffblk *ffblk);
程序例:
/* findnext example */
#include <stdio.h>
#include <dir.h>
int main(void)
{
struct ffblk ffblk;
int done;
printf(“Directory listing of *.*n”);
done = findfirst(“*.*”,&ffblk,0);
while (!done)
{
printf(” %sn”, ffblk.ff_name);
done = findnext(&ffblk);
}
return 0;
}
函數(shù)名: floodfill
功 能: 填充一個(gè)有界區(qū)域
用 法: void far floodfill(int x, int y, int border);
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, local variables */
initgraph(&gdriver, &gmode, “”);
/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk)
/* an error occurred */
{
printf(“Graphics error: %sn”,
grapherrormsg(errorcode));
printf(“Press any key to halt:”);
getch();
exit(1);
/* terminate with an error code */
}
maxx = getmaxx();
maxy = getmaxy();
/* select drawing color */
setcolor(getmaxcolor());
/* select fill color */
setfillstyle(SOLID_FILL, getmaxcolor());
/* draw a border around the screen */
rectangle(0, 0, maxx, maxy);
/* draw some circles */
circle(maxx / 3, maxy /2, 50);
circle(maxx / 2, 20, 100);
circle(maxx-20, maxy-50, 75);
circle(20, maxy-20, 25);
/* wait for a key */
getch();
/* fill in bounded region */
floodfill(2, 2, getmaxcolor());
/* clean up */
getch();
closegraph();
return 0;
}
函數(shù)名: floor
功 能: 向下舍入
用 法: double floor(double x);
程序例:
#include <stdio.h>
#include <math.h>
int main(void)
{
double number = 123.54;
double down, up;
down = floor(number);
up = ceil(number);
printf(“original number %10.2lfn”,
number);
printf(“number rounded down %10.2lfn”,
down);
printf(“number rounded up %10.2lfn”,
up);
return 0;
}
函數(shù)名: flushall
功 能: 清除所有緩沖區(qū)
用 法: int flushall(void);
程序例:
#include <stdio.h>
int main(void)
{
FILE *stream;
/* create a file */
stream = fopen(“DUMMY.FIL”, “w”);
/* flush all open streams */
printf(“%d streams were flushed.n”,
flushall());
/* close the file */
fclose(stream);
return 0;
}
函數(shù)名: fmod
功 能: 計(jì)算x對(duì)y的模, 即x/y的余數(shù)
用 法: double fmod(double x, double y);
程序例:
#include <stdio.h>
#include <math.h>
int main(void)
{
double x = 5.0, y = 2.0;
double result;
result = fmod(x,y);
printf(“The remainder of (%lf / %lf) is
%lfn”, x, y, result);
return 0;
}
函數(shù)名: fnmerge
功 能: 建立新文件名
用 法: void fnerge(char *path, char *drive, char *dir);
程序例:
#include <string.h>
#include <stdio.h>
#include <dir.h>
int main(void)
{
char s[MAXPATH];
char drive[MAXDRIVE];
char dir[MAXDIR];
char file[MAXFILE];
char ext[MAXEXT];
getcwd(s,MAXPATH); /* get the current working directory */
strcat(s,”\”); /* append on a trailing character */
fnsplit(s,drive,dir,file,ext); /* split the string to separate elems */
strcpy(file,”DATA”);
strcpy(ext,”.TXT”);
fnmerge(s,drive,dir,file,ext); /* merge everything into one string */
puts(s); /* display resulting string */
return 0;
}
函數(shù)名: fopen
功 能: 打開(kāi)一個(gè)流
用 法: FILE *fopen(char *filename, char *type);
程序例:
#include <stdlib.h>
#include <stdio.h>
#include <dir.h>
int main(void)
{
char *s;
char drive[MAXDRIVE];
char dir[MAXDIR];
char file[MAXFILE];
char ext[MAXEXT];
int flags;
s=getenv(“COMSPEC”); /* get the comspec environment parameter */
flags=fnsplit(s,drive,dir,file,ext);
printf(“Command processor info:n”);
if(flags & DRIVE)
printf(“tdrive: %sn”,drive);
if(flags & DIRECTORY)
printf(“tdirectory: %sn”,dir);
if(flags & FILENAME)
printf(“tfile: %sn”,file);
if(flags & EXTENSION)
printf(“textension: %sn”,ext);
return 0;
}
函數(shù)名: fprintf
功 能: 傳送格式化輸出到一個(gè)流中
用 法: int fprintf(FILE *stream, char *format[, argument,…]);
程序例:
/* Program to create backup of the
AUTOEXEC.BAT file */
#include <stdio.h>
int main(void)
{
FILE *in, *out;
if ((in = fopen(“\AUTOEXEC.BAT”, “rt”))
== NULL)
{
fprintf(stderr, “Cannot open input
file.n”);
return 1;
}
if ((out = fopen(“\AUTOEXEC.BAK”, “wt”))
== NULL)
{
fprintf(stderr, “Cannot open output
file.n”);
return 1;
}
while (!feof(in))
fputc(fgetc(in), out);
fclose(in);
fclose(out);
return 0;
}
函數(shù)名: FP_OFF
功 能: 獲取遠(yuǎn)地址偏移量
用 法: unsigned FP_OFF(void far *farptr);
程序例:
/* FP_OFF */
#include <dos.h>
#include <stdio.h>
int main(void)
{
char *str = “fpoff.c”;
printf(“The offset of this file in memory
is: %Fpn”, FP_OFF(str));
return 0;
}
函數(shù)名: FP_SEG
功 能: 獲取遠(yuǎn)地址段值
用 法: unsigned FP_SEG(void far *farptr);
程序例:
/* FP_SEG */
#include <dos.h>
#include <stdio.h>
int main(void)
{
char *filename = “fpseg.c”;
printf(“The offset of this file in memory
is: %Fpn”, FP_SEG(filename));
return(0);
}
函數(shù)名: fputc
功 能: 送一個(gè)字符到一個(gè)流中
用 法: int fputc(int ch, FILE *stream);
程序例:
#include <stdio.h>
int main(void)
{
char msg[] = “Hello world”;
int i = 0;
while (msg[i])
{
fputc(msg[i], stdout);
i++;
}
return 0;
}
函數(shù)名: fputchar
功 能: 送一個(gè)字符到標(biāo)準(zhǔn)輸出流(stdout)中
用 法: int fputchar(char ch);
程序例:
#include <stdio.h>
int main(void)
{
char msg[] = “This is a test”;
int i = 0;
while (msg[i])
{
fputchar(msg[i]);
i++;
}
return 0;
}
函數(shù)名: fputs
功 能: 送一個(gè)字符到一個(gè)流中
用 法: int fputs(char *string, FILE *stream);
程序例:
#include <stdio.h>
int main(void)
{
/* write a string to standard output */
fputs(“Hello worldn”, stdout);
return 0;
}
函數(shù)名: fread
功 能: 從一個(gè)流中讀數(shù)據(jù)
用 法: int fread(void *ptr, int size, int nitems, FILE *stream);
程序例:
#include <string.h>
#include <stdio.h>
int main(void)
{
FILE *stream;
char msg[] = “this is a test”;
char buf[20];
if ((stream = fopen(“DUMMY.FIL”, “w+”))
== NULL)
{
fprintf(stderr,
“Cannot open output file.n”);
return 1;
}
/* write some data to the file */
fwrite(msg, strlen(msg)+1, 1, stream);
/* seek to the beginning of the file */
fseek(stream, SEEK_SET, 0);
/* read the data and display it */
fread(buf, strlen(msg)+1, 1, stream);
printf(“%sn”, buf);
fclose(stream);
return 0;
}
函數(shù)名: free
功 能: 釋放已分配的塊
用 法: void free(void *ptr);
程序例:
#include <string.h>
#include <stdio.h>
#include <alloc.h>
int main(void)
{
char *str;
/* allocate memory for string */
str = malloc(10);
/* copy “Hello” to string */
strcpy(str, “Hello”);
/* display string */
printf(“String is %sn”, str);
/* free memory */
free(str);
return 0;
}
函數(shù)名: freemem
功 能: 釋放先前分配的DOS內(nèi)存塊
用 法: int freemem(unsigned seg);
程序例:
#include <dos.h>
#include <alloc.h>
#include <stdio.h>
int main(void)
{
unsigned int size, segp;
int stat;
size = 64; /* (64 x 16) = 1024 bytes */
stat = allocmem(size, &segp);
if (stat < 0)
printf(“Allocated memory at segment:
%xn”, segp);
else
printf(“Failed: maximum number of
paragraphs available is %un”,
stat);
freemem(segp);
return 0;
}
函數(shù)名: freopen
功 能: 替換一個(gè)流
用 法: FILE *freopen(char *filename, char *type, FILE *stream);
程序例:
#include <stdio.h>
int main(void)
{
/* redirect standard output to a file */
if (freopen(“OUTPUT.FIL”, “w”, stdout)
== NULL)
fprintf(stderr, “error redirecting
stdoutn”);
/* this output will go to a file */
printf(“This will go into a file.”);
/* close the standard output stream */
fclose(stdout);
return 0;
}
函數(shù)名: frexp
功 能: 把一個(gè)雙精度數(shù)分解為尾數(shù)的指數(shù)
用 法: double frexp(double value, int *eptr);
程序例:
#include <math.h>
#include <stdio.h>
int main(void)
{
double mantissa, number;
int exponent;
number = 8.0;
mantissa = frexp(number, &exponent);
printf(“The number %lf is “, number);
printf(“%lf times two to the “, mantissa);
printf(“power of %dn”, exponent);
return 0;
}
函數(shù)名: fscanf
功 能: 從一個(gè)流中執(zhí)行格式化輸入
用 法: int fscanf(FILE *stream, char *format[,argument…]);
程序例:
#include <stdlib.h>
#include <stdio.h>
int main(void)
{
int i;
printf(“Input an integer: “);
/* read an integer from the
standard input stream */
if (fscanf(stdin, “%d”, &i))
printf(“The integer read was: %in”,
i);
else
{
fprintf(stderr, “Error reading an
integer from stdin.n”);
exit(1);
}
return 0;
}
函數(shù)名: fseek
功 能: 重定位流上的文件指針
用 法: int fseek(FILE *stream, long offset, int fromwhere);
程序例:
#include <stdio.h>
long filesize(FILE *stream);
int main(void)
{
FILE *stream;
stream = fopen(“MYFILE.TXT”, “w+”);
fprintf(stream, “This is a test”);
printf(“Filesize of MYFILE.TXT is %ld bytesn”, filesize(stream));
fclose(stream);
return 0;
}
long filesize(FILE *stream)
{
long curpos, length;
curpos = ftell(stream);
fseek(stream, 0L, SEEK_END);
length = ftell(stream);
fseek(stream, curpos, SEEK_SET);
return length;
}
函數(shù)名: fsetpos
功 能: 定位流上的文件指針
用 法: int fsetpos(FILE *stream, const fpos_t *pos);
程序例:
#include <stdlib.h>
#include <stdio.h>
void showpos(FILE *stream);
int main(void)
{
FILE *stream;
fpos_t filepos;
/* open a file for update */
stream = fopen(“DUMMY.FIL”, “w+”);
/* save the file pointer position */
fgetpos(stream, &filepos);
/* write some data to the file */
fprintf(stream, “This is a test”);
/* show the current file position */
showpos(stream);
/* set a new file position, display it */
if (fsetpos(stream, &filepos) == 0)
showpos(stream);
else
{
fprintf(stderr, “Error setting file
pointer.n”);
exit(1);
}
/* close the file */
fclose(stream);
return 0;
}
void showpos(FILE *stream)
{
fpos_t pos;
/* display the current file pointer
position of a stream */
fgetpos(stream, &pos);
printf(“File position: %ldn”, pos);
}
函數(shù)名: fstat
功 能: 獲取打開(kāi)文件信息
用 法: int fstat(char *handle, struct stat *buff);
程序例:
#include <sysstat.h>
#include <stdio.h>
#include <time.h>
int main(void)
{
struct stat statbuf;
FILE *stream;
/* open a file for update */
if ((stream = fopen(“DUMMY.FIL”, “w+”))
== NULL)
{
fprintf(stderr, “Cannot open output
file.n”);
return(1);
}
fprintf(stream, “This is a test”);
fflush(stream);
/* get information about the file */
fstat(fileno(stream), &statbuf);
fclose(stream);
/* display the information returned */
if (statbuf.st_mode & S_IFCHR)
printf(“Handle refers to a device.n”);
if (statbuf.st_mode & S_IFREG)
printf(“Handle refers to an ordinary
file.n”);
if (statbuf.st_mode & S_IREAD)
printf(“User has read permission on
file.n”);
if (statbuf.st_mode & S_IWRITE)
printf(“User has write permission on
file.n”);
printf(“Drive letter of file: %cn”,
‘A’+statbuf.st_dev);
printf(“Size of file in bytes: %ldn”,
statbuf.st_size);
printf(“Time file last opened: %sn”,
ctime(&statbuf.st_ctime));
return 0;
}
函數(shù)名: ftell
功 能: 返回當(dāng)前文件指針
用 法: long ftell(FILE *stream);
程序例:
#include <stdio.h>
int main(void)
{
FILE *stream;
stream = fopen(“MYFILE.TXT”, “w+”);
fprintf(stream, “This is a test”);
printf(“The file pointer is at byte
%ldn”, ftell(stream));
fclose(stream);
return 0;
}
函數(shù)名: fwrite
功 能: 寫(xiě)內(nèi)容到流中
用 法: int fwrite(void *ptr, int size, int nitems, FILE *stream);
程序例:
#include <stdio.h>
struct mystruct
{
int i;
char ch;
};
int main(void)
{
FILE *stream;
struct mystruct s;
if ((stream = fopen(“TEST.$$$”, “wb”)) == NULL) /* open file TEST.$$$ */
{
fprintf(stderr, “Cannot open output file.n”);
return 1;
}
s.i = 0;
s.ch = ‘A’;
fwrite(&s, sizeof(s), 1, stream); /* write struct s to file */
fclose(stream); /* close file */
return 0;
}
