C语言库函数F类字母Word文档格式.docx

C语言库函数F类字母Word文档格式.docx

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string.h>

dos.h>

charfar*fptr;

char*str="

Hello"

;

/*allocatememoryforthefarpointer*/

fptr=farcalloc（10,sizeof（char））;

/*copy"

intoallocatedmemory*/

/*

Note:

movedataisusedbecauseyou

mightbeinasmalldatamodel,in

whichcaseanormalstringcopyroutine

cannotbeusedsinceitassumesthe

pointersizeisnear.

*/

movedata（FP_SEG（str）,FP_OFF（str）,

FP_SEG（fptr）,FP_OFF（fptr）,

strlen（str））;

/*displaystring（notetheFmodifier）*/

Farstringis:

%Fs\n"

fptr）;

/*freethememory*/

farfree（fptr）;

farcoreleft

返回远堆中未作用存储区大小

longfarcoreleft（void）;

Thedifferencebetweenthe\

highestallocatedblockinthe\

far\n"

）;

heapandthetopofthefarheap\

is:

%lubytes\n"

farcoreleft（））;

farfree

从远堆中释放一块

voidfarfree（void）;

movedataisusedbecauseyoumightbeinasmalldatamodel,

inwhichcaseanormalstringcopyroutinecan'

tbeusedsinceit

assumesthepointersizeisnear.

farmalloc

从远堆中分配存储块

voidfar*farmalloc（unsignedlongsize）;

fptr=farmalloc（10）;

movedataisusedbecausewemight

beinasmalldatamodel,inwhichcase

anormalstringcopyroutinecannotbe

usedsinceitassumesthepointersize

isnear.

farrealloc

调整远堆中的分配块

voidfar*farrealloc（voidfar*block,unsignedlongnewsize）;

Firstaddress:

%Fp\n"

fptr=farrealloc（fptr,20）;

Newaddress:

fclose

关闭一个流

intfclose（FILE*stream）;

FILE*fp;

charbuf[11]="

0123456789"

/*createafilecontaining10bytes*/

fp=fopen（"

DUMMY.FIL"

"

w"

fwrite（&

buf,strlen（buf）,1,fp）;

/*closethefile*/

fclose（fp）;

fcloseall

关闭打开流

intfcloseall（void）;

intstreams_closed;

/*opentwostreams*/

fopen（"

DUMMY.ONE"

DUMMY.TWO"

/*closetheopenstreams*/

streams_closed=fcloseall（）;

if（streams_closed==EOF）

/*issueanerrormessage*/

perror（"

Error"

else

/*printresultoffcloseall（）function*/

%dstreamswereclosed.\n"

streams_closed）;

fcvt

把一个浮点数转换为字符串

char*fcvt（doublevalue,intndigit,int*decpt,int*sign）;

stdlib.h>

conio.h>

char*string;

doublevalue;

intdec,sign;

intndig=10;

clrscr（）;

value=9.876;

string=ecvt（value,ndig,&

dec,&

sign）;

string=%sdec=%d\

sign=%d\n"

string,dec,sign）;

value=-123.45;

ndig=15;

string=ecvt（value,ndig,&

dec,&

string=%sdec=%dsign=%d\n"

string,dec,sign）;

value=0.6789e5;

/*scientific

notation*/

ndig=5;

string=%sdec=%d\

fdopen

把流与一个文件句柄相接

FILE*fdopen（inthandle,char*type）;

sys\stat.h>

fcntl.h>

io.h>

inthandle;

FILE*stream;

/*openafile*/

handle=open（"

O_CREAT,

S_IREAD│S_IWRITE）;

/*nowturnthehandleintoastream*/

stream=fdopen（handle,"

if（stream==NULL）

fdopenfailed\n"

fprintf（stream,"

Helloworld\n"

fclose（stream）;

feof

检测流上的文件结束符

intfeof（FILE*stream）;

/*openafileforreading*/

stream=fopen（"

r"

/*readacharacterfromthefile*/

fgetc（stream）;

/*checkforEOF*/

if（feof（stream））

Wehavereachedend-of-file\n"

ferror

检测流上的错误

intferror（FILE*stream）;

/*openafileforwriting*/

/*forceanerrorconditionbyattemptingtoread*/

（void）getc（stream）;

if（ferror（stream））/*testforanerroronthestream*/

/*displayanerrormessage*/

ErrorreadingfromDUMMY.FIL\n"

/*resettheerrorandEOFindicators*/

clearerr（stream）;

fflush

清除一个流

intfflush（FILE*stream）;

voidflush（FILE*stream）;

charmsg[]="

Thisisatest"

/*createafile*/

/*writesomedatatothefile*/

fwrite（msg,strlen（msg）,1,stream）;

Pressanykeytoflush\

DUMMY.FIL:

"

getch（）;

/*flushthedatatoDUMMY.FILwithout\

closingit*/

flush（stream）;

\nFilewasflushed,Pressanykey\

toquit:

voidflush（FILE*stream）

intduphandle;

/*flushthestream'

sinternalbuffer*/

fflush（stream）;

/*makeaduplicatefilehandle*/

duphandle=dup（fileno（stream））;

/*closetheduplicatehandletoflush\

theDOSbuffer*/

close（duphandle）;

fgetc

从流中读取字符

intfgetc（FILE*stream）;

charstring[]="

charch;

/*openafileforupdate*/

w+"

/*writeastringintothefile*/

fwrite（string,strlen（string）,1,stream）;

/*seektothebeginningofthefile*/

fseek（stream,0,SEEK_SET）;

do

/*readacharfromthefile*/

ch=fgetc（stream）;

/*displaythecharacter*/

putch（ch）;

}while（ch!

=EOF）;

fgetchar

intfgetchar（void）;

/*prompttheuserforinput*/

Enteracharacterfollowedby\

<

Enter>

:

"

/*readthecharacterfromstdin*/

ch=fgetchar（）;

/*displaywhatwasread*/

Thecharacterreadis:

'

%c'

\n"

ch）;

fgetpos

取得当前文件的句柄

intfgetpos（FILE*stream）;

fpos_tfilepos;

/*reportthefilepointerposition*/

fgetpos（stream,&

filepos）;

Thefilepointerisatbyte\

%ld\n"

filepos）;

fgets

从流中读取一字符串

char*fgets（char*string,intn,FILE*stream）;

charmsg[20];

/*seektothestartofthefile*/

/*readastringfromthefile*/

fgets（msg,strlen（string）+1,stream）;

/*displaythestring*/

%s"

msg）;

filelength

取文件长度字节数

longfilelength（inthandle）;

O_CREAT）;

write（handle,buf,strlen（buf））;

/*displaythesizeofthefile*/

filelengthinbytes:

%ld\n"

filelength（handle））;

close（handle）;