F.xml

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函数名:?fabs?

功??能:?返回浮点数的绝对值?

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:?%f\n",?
???number,?fabs(number));?
???return?0;?
}?
??
??
??

函数名:?farcalloc?

功??能:?从远堆栈中申请空间?

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:?%Fs\n",?fptr);?
???/*?free?the?memory?*/?
???farfree(fptr);?
???return?0;?
}?
??
??
??

函数名:?farcoreleft?

功??能:?返回远堆中未作用存储区大小?

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\?
???????????far\n");?
???printf("heap?and?the?top?of?the?far?heap\?
???????????is:?%lu?bytes\n",?farcoreleft());?
???return?0;?
}?
??
??
??

函数名:?farfree?

功??能:?从远堆中释放一块?

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:?%Fs\n",?fptr);?
???/*?free?the?memory?*/?
???farfree(fptr);?
???return?0;?
}?
??
??
??

函数名:?farmalloc?

功??能:?从远堆中分配存储块?

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:?%Fs\n",?fptr);?
???/*?free?the?memory?*/?
???farfree(fptr);?
???return?0;?
}?
??
??
??

函数名:?farrealloc?

功??能:?调整远堆中的分配块?

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:?%Fp\n",?fptr);?
???fptr?=?farrealloc(fptr,20);?
???printf("New?address??:?%Fp\n",?fptr);?
???farfree(fptr);?
???return?0;?
}?
??
??

函数名:?fclose?

功??能:?关闭一个流?

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;?
}?
??
??
??

函数名:?fcloseall?

功??能:?关闭打开流?

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;?
}?
??
??

函数名:?fcvt?

功??能:?把一个浮点数转换为字符串?

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?=?%d\n",?string,?dec,?sign);?
???value?=?-123.45;?
???ndig=?15;?
???string?=?ecvt(value,ndig,&dec,&sign);?
???printf("string?=?%s?dec?=?%d?sign?=?%d\n",?
??????????string,?dec,?sign);?
??
???value?=?0.6789e5;?/*?scientific?
????????????????????????notation?*/?
???ndig?=?5;?
???string?=?ecvt(value,ndig,&dec,&sign);?
???printf("string?=?%s???????????dec?=?%d\?
??????????sign?=?%d\n",?string,?dec,?sign);?
???return?0;?
}?
??
??
??

函数名:?fdopen?

功??能:?把流与一个文件句柄相接?

用??法:?FILE?*fdopen(int?handle,?char?*type);?

程序例:?

#include?<sys\stat.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?failed\n");?
???else?
???{?
??????fprintf(stream,?"Hello?world\n");?
??????fclose(stream);?
???}?
???return?0;?
}?
??
??

函数名:?feof?

功??能:?检测流上的文件结束符?

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-file\n");?
???/*?close?the?file?*/?
???fclose(stream);?
???return?0;?
}?
??
??

函数名:?ferror?

功??能:?检测流上的错误?

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.FIL\n");?
??????/*?reset?the?error?and?EOF?indicators?*/?
??????clearerr(stream);?
???}?
???fclose(stream);?
???return?0;?
}?
??
??
??

函数名:?fflush?

功??能:?清除一个流?

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);?
}?
??
??
??

函数名:?fgetc?

功??能:?从流中读取字符?

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;?
}?
??
??
??

函数名:?fgetchar?

功??能:?从流中读取字符?

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;?
}?
??
??
??

函数名:?fgetpos?

功??能:?取得当前文件的句柄?

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\?
??????????%ld\n",?filepos);?
???fclose(stream);?
???return?0;?
}?
??
??
??

函数名:?fgets?

功??能:?从流中读取一字符串?

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;?
}?
??
??
??

函数名:?filelength?

功??能:?取文件长度字节数?

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:?%ld\n",?
???filelength(handle));?
???/*?close?the?file?*/?
???close(handle);?
???return?0;?
}?
??
??

函数名:?fillellipse?

功??能:?画出并填充一椭圆?

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;?
}?
??
??
??

函数名:?fillpoly?

功??能:?画并填充一个多边形?

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:?%s\n",?
?????????????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;?
}?
??
??
??

函数名:?findfirst,?findnext?

功??能:?搜索磁盘目录;?取得下一个匹配的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("??%s\n",?ffblk.ff_name);?
??????done?=?findnext(&ffblk);?
???}?
???return?0;?
}?
??
??
??

函数名:?floodfill?

功??能:?填充一个有界区域?

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:?%s\n",?
?????????????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;?
}?
??
??
??

函数名:?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?????%10.2lf\n",?
??????????number);?
???printf("number?rounded?down?%10.2lf\n",?
??????????down);?
???printf("number?rounded?up???%10.2lf\n",?
??????????up);?
???return?0;?
}?
??
??
??

函数名:?flushall?

功??能:?清除所有缓冲区?

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;?
}?
??
??
??

函数名:?fmod?

功??能:?计算x对y的模,?即x/y的余数?

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?\?
??????????%lf\n",?x,?y,?result);?
???return?0;?
}?
??
??
??

函数名:?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;?
}?
??
??
??

函数名:?fopen?

功??能:?打开一个流?

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:?%s\n",drive);?
????if(flags?&?DIRECTORY)?
???????printf("\tdirectory:?%s\n",dir);?
????if(flags?&?FILENAME)?
???????printf("\tfile:?%s\n",file);?
????if(flags?&?EXTENSION)?
???????printf("\textension:?%s\n",ext);?
????return?0;?
}?
??

函数名:?fprintf?

功??能:?传送格式化输出到一个流中?

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;?
}?
??
??
??

函数名:?FP_OFF?

功??能:?获取远地址偏移量?

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:?%Fp\n",?FP_OFF(str));?
???return?0;?
}?
??
??

函数名:?FP_SEG?

功??能:?获取远地址段值?

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:?%Fp\n",?FP_SEG(filename));?
???return(0);?
}?
??
??
??

函数名:?fputc?

功??能:?送一个字符到一个流中?

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;?
}?
??
??
??

函数名:?fputchar?

功??能:?送一个字符到标准输出流(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;?
}?
??
??
??

函数名:?fputs?

功??能:?送一个字符到一个流中?

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?world\n",?stdout);?
???return?0;?
}?
??
??
??

函数名:?fread?

功??能:?从一个流中读数据?

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("%s\n",?buf);?
???fclose(stream);?
???return?0;?
}?
??
??

函数名:?free?

功??能:?释放已分配的块?

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?%s\n",?str);?
???/*?free?memory?*/?
???free(str);?
???return?0;?
}?
??

函数名:?freemem?

功??能:?释放先前分配的DOS内存块?

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:\?
??????%x\n",?segp);?
???else?
??????printf("Failed:?maximum?number?of\?
??????paragraphs?available?is?%u\n",?
??????stat);?
???freemem(segp);?
???return?0;?
}?
??
??

函数名:?freopen?

功??能:?替换一个流?

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\?
??????????????stdout\n");?
???/*?this?output?will?go?to?a?file?*/?
???printf("This?will?go?into?a?file.");?
???/*?close?the?standard?output?stream?*/?
???fclose(stdout);?
???return?0;?
}?
??
??
??

函数名:?frexp?

功??能:?把一个双精度数分解为尾数的指数?

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?%d\n",?exponent);?
???return?0;?
}?
??
??

函数名:?fscanf?

功??能:?从一个流中执行格式化输入?

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:?%i\n",?
?????????????i);?
???else?
???{?
??????fprintf(stderr,?"Error?reading?an?\?
??????????????integer?from?stdin.\n");?
??????exit(1);?
???}?
???return?0;?
}?
??
??
??

函数名:?fseek?

功??能:?重定位流上的文件指针?

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?bytes\n",?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;?
}?
??
??
??
??
??

函数名:?fsetpos?

功??能:?定位流上的文件指针?

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:?%ld\n",?pos);?
}?
??

函数名:?fstat?

功??能:?获取打开文件信息?

用??法:?int?fstat(char?*handle,?struct?stat?*buff);?

程序例:?

#include?<sys\stat.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:?%c\n",?
???‘A‘+statbuf.st_dev);?
???printf("Size?of?file?in?bytes:?%ld\n",?
???statbuf.st_size);?
???printf("Time?file?last?opened:?%s\n",?
???ctime(&statbuf.st_ctime));?
???return?0;?
}?
??
??
??

函数名:?ftell?

功??能:?返回当前文件指针?

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?\?
??????????%ld\n",?ftell(stream));?
???fclose(stream);?
???return?0;?
}?
??
??
??

函数名:?fwrite?

功??能:?写内容到流中?

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;?
}?
??
??