C语言函数大全Word下载.docx
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z.y=1.0;
val=cabs(z);
printf("
Theabsolutevalueof%.2lfi%.2lfjis%.2lf"
z.x,z.y,val);
return0;
}
calloc
分配主存储器
void*calloc(size_tnelem,size_telsize);
alloc.h>
char*str=NULL;
/*allocatememoryforstring*/
str=calloc(10,sizeof(char));
/*copy"
Hello"
intostring*/
strcpy(str,"
);
/*displaystring*/
Stringis%s\n"
str);
/*freememory*/
free(str);
ceil
向上舍入
doubleceil(doublex);
doublenumber=123.54;
doubledown,up;
down=floor(number);
up=ceil(number);
originalnumber
%5.2lf\n"
number);
numberroundeddown%5.2lf\n"
down);
numberroundedup
up);
cgets
从控制台读字符串
char*cgets(char*str);
conio.h>
charbuffer[83];
char*p;
/*There'
sspacefor80charactersplustheNULLterminator*/
buffer[0]=81;
Inputsomechars:
"
p=cgets(buffer);
\ncgetsread%dcharacters:
\"
%s\"
\n"
buffer[1],p);
Thereturnedpointeris%p,buffer[0]isat%p\n"
p,&
buffer);
/*Leaveroomfor5charactersplustheNULLterminator*/
buffer[0]=6;
chdir
改变工作目录
intchdir(constchar*path);
stdlib.h>
dir.h>
charold_dir[MAXDIR];
charnew_dir[MAXDIR];
if(getcurdir(0,old_dir))
{
perror("
getcurdir()"
exit
(1);
}
Currentdirectoryis:
\\%s\n"
old_dir);
if(chdir("
\\"
))
chdir()"
if(getcurdir(0,new_dir))
Currentdirectoryisnow:
new_dir);
\nChangingbacktoorignaldirectory:
if(chdir(old_dir))
_chmod,chmod
改变文件的访问方式
intchmod(constchar*filename,intpermiss);
sys\stat.h>
io.h>
voidmake_read_only(char*filename);
make_read_only("
NOTEXIST.FIL"
MYFILE.FIL"
voidmake_read_only(char*filename)
intstat;
stat=chmod(filename,S_IREAD);
if(stat)
Couldn'
tmake%sread-only\n"
filename);
else
Made%sread-only\n"
chsize
改变文件大小
intchsize(inthandle,longsize);
string.h>
fcntl.h>
inthandle;
charbuf[11]="
0123456789"
;
/*createtextfilecontaining10bytes*/
handle=open("
DUMMY.FIL"
O_CREAT);
write(handle,buf,strlen(buf));
/*truncatethefileto5bytesinsize*/
chsize(handle,5);
/*closethefile*/
close(handle);
circle
在给定半径以(x,y)为圆心画圆
voidfarcircle(intx,inty,intradius);
graphics.h>
/*requestautodetection*/
intgdriver=DETECT,gmode,errorcode;
intmidx,midy;
intradius=100;
/*initializegraphicsandlocalvariables*/
initgraph(&
gdriver,&
gmode,"
/*readresultofinitialization*/
errorcode=graphresult();
if(errorcode!
=grOk)
/*anerroroccurred*/
Graphicserror:
%s\n"
grapherrormsg(errorcode));
Pressanykeytohalt:
getch();
/*terminatewithanerrorcode*/
midx=getmaxx()/2;
midy=getmaxy()/2;
setcolor(getmaxcolor());
/*drawthecircle*/
circle(midx,midy,radius);
/*cleanup*/
closegraph();
cleardevice
清除图形屏幕
voidfarcleardevice(void);
/*forcenteringscreenmessages*/
settextjustify(CENTER_TEXT,CENTER_TEXT);
/*outputamessagetothescreen*/
outtextxy(midx,midy,"
pressanykeytoclearthescreen:
/*waitforakey*/
/*clearthescreen*/
cleardevice();
/*outputanothermessage*/
pressanykeytoquit:
clearerr
复位错误标志
voidclearerr(FILE*stream);
FILE*fp;
charch;
/*openafileforwriting*/
fp=fopen("
"
w"
/*forceanerrorconditionbyattemptingtoread*/
ch=fgetc(fp);
%c\n"
ch);
if(ferror(fp))
/*displayanerrormessage*/
ErrorreadingfromDUMMY.FIL\n"
/*resettheerrorandEOFindicators*/
clearerr(fp);
fclose(fp);
clearviewport
清除图形视区
voidfarclearviewport(void);
#defineCLIP_ON1
/*activatesclippinginviewport*/
intht;
ht=textheight("
W"
/*messageindefaultfull-screenviewport*/
outtextxy(0,0,"
*<
--(0,0)indefaultviewport"
/*createasmallerviewport*/
setviewport(50,50,getmaxx()-50,getmaxy()-50,CLIP_ON);
/*displaysomemessages*/
--(0,0)insmallerviewport"
outtextxy(0,2*ht,"
Pressanykeytoclearviewport:
/*cleartheviewport*/
clearviewport();
Pressanykeytoquit:
_close,close
关闭文件句柄
intclose(inthandle);
main()
/*createafilecontaining10bytes*/
NEW.FIL"
if(handle>
-1)
Erroropeningfile\n"
clock
确定处理器时间
clock_tclock(void);
time.h>
dos.h>
clock_tstart,end;
start=clock();
delay(2000);
end=clock();
Thetimewas:
%f\n"
(end-start)/CLK_TCK);
closegraph
关闭图形系统
voidfarclosegraph(void);
intx,y;
/*initializegraphicsmode*/
/*anerror
occurred*/
x=getmaxx()/2;
y=getmaxy()/2;
/*outputamessage*/
outtextxy(x,y,"
Pressakeytoclosethegraphicssystem:
/*closesdownthegraphicssystem*/
We'
renowbackintextmode.\n"
clreol
在文本窗口中清除字符到行末
voidclreol(void);
clrscr();
cprintf("
ThefunctionCLREOLclearsallcharactersfromthe\r\n"
cursorpositiontotheendofthelinewithinthe\r\n"
currenttextwindow,withoutmovingthecursor.\r\n"
Pressanykeytocontinue..."
gotoxy(14,4);
clreol();