C語(yǔ)言函數(shù)詳解

函數(shù)A函數(shù)名:abort功能:異常終止ー個(gè)進(jìn)程用法:voidabort(void);程序例:ttinclude<stdio.h>#include<stdlib.h>intmain(void)(printf(z，Callingabort()\nz，);abort();return0;/*Thisisneverreached*/)函數(shù)名:abs功能:求整數(shù)的絕對(duì)值用法:intabs(inti);程序例:Sinclude<stdio.h>Sinclude<math.h>intmain(void)(intnumber=-1234;printf(z，number:%dabsolutevalue:%d\n,number,abs(number));return0;)函數(shù)名:absread,abswirte功能:絕對(duì)磁盤扇區(qū)讀、寫數(shù)據(jù)用法:intabsread(intdrive,intnsects,intsectno,void*buffer);intabswrite(intdrive,intnsects,intsectno,void*buffer);程序例:/*absreadexample*/#include<stdio.h>#include<conio.h>#include<process.h>#include<dos.h>intmain(void)inti,strt,ch_out,sector;charbuf[512];printf("InsertadisketteintodriveAandpressanykey\n");getchO;sector=0;if(absread(0,1,sector,&buf)!=0)(perror("Diskproblem");exit(1);)printf("Read0K\n");strt=3;for(i=0;i<80;i++)(ch_out=buf[strt+i];putchar(ch_out);)printf("\n");return(0);函數(shù)名:access功能:確定文件的訪問(wèn)權(quán)限用法:intaccess(constchar*filename,intamode);程序例:#include<stdio.h>#include<io.h>intfile_exists(char*filename);intmain(void)(printf("DoesNOTEXIST.FILexist:%s\n",file_exists("NOTEXISTS.FIL")?"YES":"NO");return0;intfile_exists(char*filename)(return(access(filename,0)==0);函數(shù)名:acos功能:反余弦函數(shù)用法:doubleacos(doublex);程序例:#include<stdio.h>#include<math.h>intmain(void)(doubleresult;doublex=0.5;result=acos(x);printf〈Thearccosineof%lfis%lf\n〃,x,result);return0;)函數(shù)名:allocmem功能:分配DOS存儲(chǔ)段用法:intallocmem(unsignedsize,unsigned*seg);程序例:#include<dos.h>#include<alloc.h>Sinclude<stdio.h>intmain(void)|unsignedintsize,segp;intstat;size=64;/*(64x16)=1024bytes*/stat=allocmem(size,&segp);if(stat==-1)printf("Allocatedmemoryatsegment:%x\n",segp);elseprintf("Failed:maximumnumberofparagraphsavailableis%u\n",stat);return0;)函數(shù)名:arc功能:畫一弧線用法:voidfararc(intx,inty,intstangle,intendangle,intradius);程序例:ttinclude<graphics.h>#include<stdlib.h>Sinclude<stdio.h>Sinclude<conio.h>intmain(void)|/*requestautodetection*/intgdriver=DETECT,gmode,errorcode;intmidx,midy;intstangle=45,endangle=135;intradius=100;/*initializegraphicsandlocalvariables*/initgraph(&gdriver,&gmode,〃“)；/*readresultofinitialization*/errorcode=graphresult();/*anerroroccurred*/if(errorcode!=grOk)(printf("Graphicserror:%s\n",grapherrormsg(errorcode));printf("Pressanykeytohalt:");getchO;exit(1);/*terminatewithanerrorcode*/)midx=getmaxx()/2;midy=getmaxy()/2;setcolor(getmaxcolor());/*drawarc*/arc(midx,midy,stangle,endangle,radius);/*cleanup*/getchO;closegraph();return0;)函數(shù)名:asctime功能:轉(zhuǎn)換日期和時(shí)間為ASCII碼用法:char*asctime(conststructtm*tblock);程序例:ttinclude<stdio.h>ttinclude<string.h>Sinclude<time.h>intmain(void){structtmt;charstr[80];/*sampleloadingoftmstructure*/t.tm_sec=1;/*Seconds*/t.tm_min=30;/*Minutes*/t.tm_hour=9;/*Hour*/t.tm_mday=22;/*DayoftheMonth*/t.tm_mon=11;/*Month*/t.tm_year=56;/*Year-doesnotincludecentury*/t.tm_wday=4;/*Dayoftheweek*/t.tm_yday=0;/*Doesnotshowinasctime*/t.tm_isdst=0;/*IsDaylightSavTime;doesnotshowinasctime*//*convertsstructuretonullterminatedstring*/strcpy(str,asctime(&t));printf("%s\n",str);return0;函數(shù)名:asin功能:反正弦函數(shù)用法:doubleasin(doublex);程序例:Sinclude<stdio.h>Sinclude<math.h>intmain(void)(doubleresult;doublex=0.5;result=asin(x);printf(z，Thearcsinof%lfis%lf\n,x,result);return(0);函數(shù)名:assert功能:測(cè)試ー個(gè)條件并可能使程序終止用法:voidassert(inttest);程序例:Sinclude<assert.h>Sinclude<stdio.h>#include<stdlib.h>structITEM{intkey;intvalue;)；/*additemtolist,makesurelistisnotnull*/voidadditem(structITEM*itemptr){assert(itemptr!=NULL);/*additemtolist*/)intmain(void)(additem(NULL);return0;函數(shù)名:atan功能:反正切函數(shù)用法:doubleatan(doublex);程序例:ttinclude<stdio.h>#include<math.h>intmain(void){doubleresult;doublex=0.5;result=atan(x);printf(z，Thearctangentof%lfis%lf\n”,x,result);return(0);函數(shù)名:atan2功能:計(jì)算Y/X的反正切值用法:doubleatan2(doubley,doublex);程序例:#include<stdio.h>ttinclude<math.h>intmain(void)(doubleresult;doublex=90.0,y=45.0;result=atan2(y,x);printf(Z/Thearctangentratioof%lfis%lf\n，z,(y/x),result);return0;)函數(shù)名:atexit功能:注冊(cè)終止函數(shù)用法:intatexit(atexit_tfunc);程序例:#include<stdio.h>#include<stdlib.h>voidexit_fnl(void)(printflExitfunction#1called\n〃)；)voidexit_fn2(void)(printf(Z/Exitfunction#2called'n");)intmain(void)(/*postexitfunction#1*/atexit(exit_fnl);/*postexitfunction#2*/atexit(exit_fn2);return0;米。?a十cf功能:把字符串轉(zhuǎn)換成浮點(diǎn)數(shù)用法:doubleatof(constchar*nptr);程序例:#include<stdlib.h>ttinclude<stdio.h>intmain(void)(floatf;char*str="12345.67”;f=atof(str);printf("string=%sfloat=%f\n",str,f);return0;)函數(shù)名:atoi功能:把字符串轉(zhuǎn)換成長(zhǎng)整型數(shù)用法:intatoi(constchar*nptr);程序例:#include<stdlib.h>#include<stdio.h>intmain(void)(intn;char*str="12345.67";n=atoi(str);printf("string=%sinteger=%d\n",str,n);return0;)函數(shù)名:atoi功能:把字符串轉(zhuǎn)換成長(zhǎng)整型數(shù)用法:longatoi(constchar*nptr);程序例:#include<stdlib.h>Sinclude<stdio.h>intmain(void)long1;char*str="98765432”;1=atol(Istr);printf("string=%sinteger=%ld\n",str,1);return(0);函數(shù)B函數(shù)名:bar功能:畫一個(gè)二維條形圖用法:voidfarbar(intleft,inttop,intright,intbottom);程序例:#include<graphics.h>#include<stdlib.h>#include<stdio.h>#include<conio.h>intmain(void)|/*requestautodetection*/intgdriver=DETECT,gmode,errorcode;intmidx,midy,i;/*initializegraphicsandlocalvariables*/initgraph(&gdriver,&gmode,"");/*readresultofinitialization*/errorcode=graphresult();if(errorcode!=grOk)/*anerroroccurred*/(printf("Graphicserror:%s\n",grapherrormsg(errorcode));printf("Pressanykeytohalt:");getchO;exit(1);/*terminatewithanerrorcode*/midx=getmaxx()/2;midy=getmaxy()/2;/*loopthroughthefillpatterns*/for(i二SOL1D_F1LL;i<USER_FILL;i++)(/*setthefillstyle*/setfi1Istyle(i,getmaxcolor());/*drawthebar*/bar(midx-50,midy-50,midx+50,midy+50);getchO;)/*cleanup*/closegraph();return0;函數(shù)名:bar3d功能:畫一個(gè)三維條形圖用法:voidfarbar3d(intleft,inttop,intright,intbottom,intdepth,inttopflag);程序例:#include<graphics.h>#include<stdlib.h>#include<stdio.h>#include<conio.h>intmain(void)|/*requestautodetection*/intgdriver=DETECT,gmode,errorcode;intmidx,midy,i;/*initializegraphics,localvariables*/initgraph(&gdriver,&gmode,);/*readresultofinitialization*/errorcode=graphresult();if(errorcode!=grOk)/*anerroroccurred*/(printf("Graphicserror:%s\n",grapherrormsg(errorcode));printf("Pressanykeytohalt:");getchO;exit(1);/*terminatewitherrorcode*/)midx=getmaxx()/2;midy=getmaxy()/2;/*loopthroughthefillpatterns*/for(i=EMPTY_FILL;i<USER_FILL;i++)(/*setthefillstyle*/setfi1Istyle(i,getmaxcolor());/*drawthe3-dbar*/bar3d(midx-50,midy-50,midx+50,midy+50,10,1);getchO;)/*cleanup*/closegraph();return0;函數(shù)名:bdos功能:DOS系統(tǒng)調(diào)用用法:intbdos(intdosfun,unsigneddosdx,unsigneddosal);程序例:ttinclude<stdio.h>ttinclude<dos.h>/*Getcurrentdriveas'A','B',...*/charcurrent_drive(void)(charcurdrive;/*Getcurrentdiskas0,1,...*/curdrive=bdos(0x19,0,0);return('A'+curdrive);intmain(void)printf(zzThecurrentdriveis%c:\n”,current_drive());return0;函數(shù)名:bdosptr功能:DOS系統(tǒng)調(diào)用用法:intbdosptr(intdosfun,void*argument,unsigneddosal);程序例:#include<string.h>#include<stdio.h>#include<dir.h>#include<dos.h>Sinclude<errno.h>#include<stdlib.h>#defineBUFLEN80intmain(void)|charbuffer[BUFLEN];inttest;printf(z，Enterfullpathnameofadirectory、?！?；gets(buffer);test=bdosptr(0x3B,buffer,0);if(test)(printf〈DOSerrormessage:%d\n",errno);/*Seeerrno.hforerrorlistings*/exit(1);)getcwd(buffer,BUFLEN);printf("Thecurrentdirectoryis:%s\n",buffer);return0;函數(shù)名:bioscom功能:串行I/O通信用法:intbioscom(intcmd,charabyte,intport);程序例:#include<bios.h>Sinclude<conio.h>#defineCOM10#defineDATA_READY0x100#defineTRUE1SdefineFALSE0#defineSETTINGS(0x80 0x02 0x00 0x00)intmain(void)(intin,out,status,DONE=FALSE;bioscom(0,SETTINGS,COMl);cprintfC...BIOSCOM[ESC]toexit...\n");while(!D0NE){status=bioscom(3,0,COMl);if(status&DATA_READY)if((out=bioscom(2,0,COMl)&0x7F)[=0)putch(out);if(kbhit()){if((in=getchO)=='\xlB')DONE=TRUE;bioscom(l,in,COMl);))return0;函數(shù)名:biosdisk功能:軟硬盤1/0用法：intbiosdisk(intcmd,intdrive,inthead,inttrack,intsectorintnsects,void*buffer);程序例：#include<bios.h>Sinclude<stdio.h>intmain(void)(intresult;charbuffer[512];printf("Testingtoseeifdrivea:isready\n");result=biosdisk(4,0,0,0,0,1,buffer);result&二0x02;(result)?(printf("DriveA:Ready\n")):(printf("DriveA:NotReady\n"));return0;函數(shù)名:biosequip功能:檢查設(shè)備用法:intbiosequip(void);程序例:#include<bios.h>#include<stdio.h>intmain(void)(intresult;charbuffer[512];printf("Testingtoseeifdrivea:isready\n");result=biosdisk(4,0,0,0,0,1,buffer);result&=0x02;(result)?(printf("DriveA:Ready\n")):(printf("DriveA:NotReadハn"));return0;函數(shù)名:bioskey功能:直接使用BIOS服務(wù)的鍵盤接口用法:intbioskey(intcmd);程序例:ttinclude<stdio.h>Sinclude<bios.h>Sinclude<ctype.h>#defineRIGHT0x01#defineLEFT0x02ttdefineCTRL0x04#defineALT0x08intmain(void)(intkey,modifiers;/*function1returns0untilakeyispressed*/while(bioskey(1)==0);/*function0returnsthekeythatiswaiting*/key=bioskey(0);/*usefunction2todetermineifshiftkeyswereused*/modifiers=bioskey(2);if(modifiers)(printf("[”);if(modifiers&RIGHT)printf("RIGHT");if(modifiers&LEFT)printf("LEFT");if(modifiers&CTRL)printf("CTRL");if(modifiers&ALT)printf("ALT");printf("]");)/*printoutthecharacterread*/if(isalnum(key&OxFF))printf("'%c\n",key);elseprintf("%#02x\n",key);return0;函數(shù)名:biosmemory功能:返回存儲(chǔ)塊大小用法:intbiosmemory(void);程序例:#include<stdio.h>#include<bios.h>intmain(void)(intmemory_size;memory_size=biosmemory();/*returnsvalueupto640K*/printf(Z，RAMsize=%dK\n，z,memory_size);return0;函數(shù)名:biosprint功能:直接使用BIOS服務(wù)的打印機(jī)I/O用法:intbiosprint(intcmd,intbyte,intport);程序例:#include<stdio.h>#include<conio.h>#include<bios.h>intmain(void)|#defineSTATUS2/*printerstatuscommand*/#definePORTNUM0/*portnumberforLPT1*/intstatus,abyte=0;printf(zzPleaseturnoffyourprinter.Pressanykeytocontinue'n");getchO;status=biosprint(STATUS,abyte,PORTNUM);if(status&0x01)printf(""Devicetimeout.\n〃)；if(status&0x08)printf(zzI/0error.\nzz);if(status&0x10)printf(zzSelected.\n");if(status&0x20)printf(z，0utofpaper.\n");if(status&0x40)printf(zzAcknowledge.\n);if(status&0x80)printf(zzNotbusy.\n，z);

return0;函數(shù)名:biostime功能:讀取或設(shè)置BIOS時(shí)間用法:longbiostime(intcmd,longnewtime);程序例:#include<stdio.h>#include<bios.h>#include<time.h>#include<conio.h>intmain(void)(longbios_time;clrscr();cprintf〈Thecprintf("The

cprintf("Thecprintf〈Thecprintf("The

cprintf("Thenumberofsecondssincemidnightis:\r\n");

numberofminutessincemidnightis:\r\n");cprintf("Thenumberofhourssincemidnightis:\r\n");cprintf("Thenumberofhourssincemidnightis:\r\n");cprintf("\r\nPressanykeytoquit:");while(!kbhit())bios_time=biostime(0,0L);gotoxy(50,1);cprintf("%lu",bios_time);gotoxy(50,2);cprintf("%.4f",bios_time/CLK_TCK);gotoxy(50,3);cprintf("%.4f”,bios_time/CLK_TCK/60);gotoxy(50,4);cprintfC%.4f",bios_time/CLK_TCK/3600);return0;函數(shù)名:brk功能:改變數(shù)據(jù)段空間分配用法:intbrk(void*endds);程序例:#include<stdio.h>ttinclude<alloc.h>intmain(void)(char*ptr;printf〈Changingallocationwithbrk()\n〃)；ptr=malloc(1);printf(z，Beforebrk()call:%lubytesfree\n",coreleft());brk(ptr+1000);printf(，zAfterbrk()cal1:%lubytesfree\n〃,coreleft());return0;函數(shù)名:bsearch功能:二分法搜索用法:void*bsearch(constvoid*key,constvoid*base,size_t*nelem,size_twidth,int(*fcmp)(constvoid*,const*));程序例:#include<stdlib.h>#include<stdio.h>ttdefineNELEMS(arr)(sizeof(arr)/sizeof(arr[0]))intnumarray[]={123,145,512,627,800,933};intnumeric(constint*pl,constint*p2){return(*pl-*p2);)intlookup(intkey)(inttemptr;/*Thecastof(int(*)(constvoid*,constvoid*))isneededtoavoidatypemismatcherroratcompiletime*/itemptr=bsearch(&key,numarray,NELEMS(numarray),sizeof(int),(int(*)(constvoid*,constvoid*))numeric);return(itemptr!=NULL);)intmain(void)(if(lookup(512))printf(z，512isinthetable.\n，z);elseprintf(z，512isntinthetable.\n，z);return0;函數(shù)C函數(shù)名:cabs功能:計(jì)算復(fù)數(shù)的絕對(duì)值用法:doublecabs(structcomplexz);程序例:#include<stdio.h>Sinclude<math.h>intmain(void)(structcomplexz;doubleval;z.x=2.0;z.y=1.0;val=cabs(z);printf(zzTheabsolutevalueof%.21fi%.21fjis%.21fzz,z.x,z.y,val);return0;)函數(shù)名:calloc功能:分配主存儲(chǔ)器用法:void*calloc(size_tnelem,size_telsize);程序例:ttinclude<stdio.h>Sinclude<alloc.h>intmain(void)(char*str=NULL;/*allocatememoryforstring*/str=calloc(10,sizeof(char));/*copy"Hello"intostring*/strcpy(str,"Hello");/*displaystring*/printf(z，Stringis%s\n",str);/*freememory*/free(str);return0;函數(shù)名:ceil功能:向上舍入用法:doublecei1(doublex);程序例:Sinclude<math.h>#include<stdio.h>intmain(void)(doublenumber=123.54;doubledown,up;down=floor(number);up=ceil(number);printf(zzoriginalnumber%5.21f\n",number);printf("numberroundeddown%5.21f\n",down);printf("numberroundedup%5.21f\n",up);return0;函數(shù)名:cgets功能:從控制臺(tái)讀字符串用法:char*cgets(char*str);程序例:#include<stdio.h>#include<conio.h>intmain(void)(charbuffer[83];char*p;/*There'sspacefor80charactersplustheNULLterminator*/buffer[0]=81;printf("Inputsomechars:");p=cgets(buffer);printf("\ncgetsread%dcharacters:\"%s\"\n",buffer[1],p);printf("Thereturnedpointeris%p,buffer[0]isat%p\n",p,&buffer);/*Leaveroomfor5charactersplustheNULLterminator*/buffer[0]=6;printf("Inputsomechars:");p=cgets(buffer);printf("\ncgetsread%dcharacters:\"%s\"\n",buffer[1],p);printf("Thereturnedpointeris%p,buffer[0]isat%p\n",p,&buffer);return0;函數(shù)名:chdir功能:改變工作目錄用法:intchdir(constchar*path);程序例:#include<stdio.h>#include<stdlib.h>#include<dir.h>charold_dir[MAXDIR];charnewdir[MAXDIR];intmain(void)(if(getcurdir(0,old_dir))|perror("getcurdir()");exit(1);)printf("Currentdirectoryis:\\%s\n",old_dir);if(chdir("\\"))(perror("chdir()");exit(1);)if(getcurdir(0,newdir))(perror("getcurdir()");exit(1);)printf("Currentdirectoryisnow:\\%s\n",newdir);printf("\nChangingbacktoorignaldirectory:\\%s\n",old_dir);if(chdir(old_dir))|perror("chdir()");exit(1);)return0;)函數(shù)名:_chmod,chmod功能:改變文件的訪問(wèn)方式用法:intchmod(constchar*filename,intpermiss);程序例:#include<sys\stat.h>Sinclude<stdio.h>#include<io.h>voidmake_read_on1y(char*filename);intmain(void)(make_read_onlyCNOTEXIST.FIL");make_read_onlyCMYFILE.FIL");return0;)voidmake_read_only(char*filename)(intstat;stat=chmod(filename,S_IREAD);if(stat)printf("Couldn*tmake%sread-only\n〃,filename);elseprintf("Made%sread-only\n",filename);函數(shù)名:chsize功能:改變文件大小用法:intchsize(inthandle,longsize);程序例:Sinclude<string.h>#include<fcntl.h>ttinclude<io.h>intmain(void)(inthandle;charbuf[ll]="0123456789";/*createtextfilecontaining10bytes*/handle=open("DUMMY.FIL",0_CREAT);write(handle,buf,strlen(buf));/*truncatethefileto5bytesinsize*/chsize(handle,5);/*closethefile*/close(handle);return0;函數(shù)名:circle功能:在給定半徑以(x,y)為圓心畫圓用法:voidfarcircle(intx,inty,intradius);程序例:#include<graphics.h>ttinclude<stdlib.h>Sinclude<stdio.h>Sinclude<conio.h>intmain(void)(/*requestautodetection*/intgdriver=DETECT,gmode,errorcode;intmidx,midy;intradius=100;/*initializegraphicsandlocalvariables*/initgraph(&gdriver,&gmode,);/*readresultofinitialization*/errorcode=graphresult();if(errorcode!=grOk)/*anerroroccurred*/(printf〈Graphicserror:%s\n〃,grapherrormsg(errorcode));printfiPressanykeytohalt:");getchO;exit(1);/*terminatewithanerrorcode*/)midx=getmaxx()/2;midy=getmaxy()/2;setcolor(getmaxcolor());/*drawthecircle*/circle(midx,midy,radius);/*cleanup*/getchO;closegraph();return0;函數(shù)名:cleardevice功能:清除圖形屏幕用法:voidfarcleardevice(void);程序例:#include<graphics.h>ttinclude<stdlib.h>Sinclude<stdio.h>Sinclude<conio.h>intmain(void)(/*requestautodetection*/intgdriver=DETECT,gmode,errorcode;intmidx,midy;/*initializegraphicsandlocalvariables*/initgraph(&gdriver,&gmode,);/*readresultofinitialization*/errorcode=graphresult();if(errorcode!=grOk)/*anerroroccurred*/(printf〈Graphicserror:%s\n〃,grapherrormsg(errorcode));printf(''Pressanykeytohalt:");getchO;exit(1);/*terminatewithanerrorcode*/)midx=getmaxx()/2;midy=getmaxy()/2;setcolor(getmaxcolor());/*forcenteringscreenmessages*/settextjustify(CENTER_TEXT,CENTER_TEXT);/*outputamessagetothescreen*/outtextxy(midx,midy,"pressanykeytoclearthescreen:");/*waitforakey*/getchO;/*clearthescreen*/cleardevice();/*outputanothermessage*/outtextxy(midx,midy,“pressanykeytoquit:");/*cleanup*/getchO;closegraph();return0;函數(shù)名:clearerr功能:復(fù)位錯(cuò)誤標(biāo)志用法:voidclearerr(FILE*stream);程序例:#include<stdio.h>intmain(void)(FILE*fp;charch;/*openafileforwriting*/fp=fopen("DUMMY.FIL","w");/*forceanerrorconditionbyattemptingtoread*/ch=fgetc(fp);printf("%c\n",ch);if(ferror(fp)){/*displayanerrormessage*/printf("ErrorreadingfromDUMMY.FIL\n");/*resettheerrorandEOFindicators*/clearerr(fp);)fclose(fp);return0;函數(shù)名:clearviewport功能:清除圖形視區(qū)用法:voidfarclearviewport(void);程序例:Sinclude<graphics.h>#include<stdlib.h>#include<stdio.h>ttinclude<conio.h>#defineCLIP_ON1/*activatesclippinginviewport*/intmain(void)(/*requestautodetection*/intgdriver=DETECT,gmode,errorcode;intht;/*initializegraphicsandlocalvariables*/initgraph(&gdriver,&gmode,);/*readresultofinitialization*/errorcode=graphresult();if(errorcode!=grOk)/*anerroroccurred*/(printfiGraphicserror:%s\n〃,grapherrormsg(errorcode));printfiPressanykeytohalt:");getchO;exit(1);/*terminatewithanerrorcode*/)setcolor(getmaxcolor());ht=textheight("W");/*messageindefaultfull-screenviewport*/outtextxy(0,0,“*<--(0,0)indefaultviewport");/*createasmallerviewport*/setviewport(50,50,getmaxx()-50,getmaxy()-50,CLIP_ON);/*displaysomemessages*/outtextxy(0,0,"*<--(0,0)insmallerviewport");outtextxy(0,2*ht,"Pressanykeytoclearviewport:");/*waitforakey*/getchO;/*cleartheviewport*/clearviewport();/*outputanothermessage*/outtextxy(0,0,"Pressanykeytoquit:");/*cleanup*/getchO;closegraph();return0;函數(shù)名:_close,close功能:実閉文件句柄用法:intclose(inthandle);程序例:Sinclude<string.h>#include<stdio.h>#include<fcntl.h>#include<io.h>main()(inthandle;charbuf[ll]="0123456789";/*createafilecontaining10bytes*/handle=open("NEW.FIL",O_CREAT);if(handle>-1)(write(handle,buf,strlen(buf));/*closethefile*/close(handle);)else{printf("Erroropeningfile\n");return0;函數(shù)名:clock功能:確定處理器時(shí)間用法:clock_tclock(void);程序例:#include<time.h>ttinclude<stdio.h>Sinclude<dos.h>intmain(void)(clock_tstart,end;start=clockO;delay(2000);end=clock();printf("Thetimewas:%f\n”,(end-start)/CLK_TCK);return0;)函數(shù)名:closegraph功能:關(guān)閉圖形系統(tǒng)用法:voidfarclosegraph(void);程序例:Sinclude<graphics.h>#include<stdlib.h>ttinclude<stdio.h>ttinclude<conio.h>intmain(void)(/*requestautodetection*/intgdriver=DETECT,gmode,errorcode;intx,y;/*initializegraphicsmode*/initgraph(&gdriver,&gmode,);/*readresultofinitialization*/errorcode=graphresult();if(errorcode!=grOk)/*anerroroccurred*/printf("Graphicserror:%s\n〃,grapherrormsg(errorcode));printf("Pressanykeytohalt:");getchO;exit(1);/*terminatewithanerrorcode*/)x=getmaxx()/2;y=getmaxy()/2;/*outputamessage*/settextjustify(CENTER_TEXT,CENTER_TEXT);outtextxy(x,y,"Pressakeytoclosethegraphicssystem:");/*waitforakey*/getchO;/*closesdownthegraphicssystem*/closegraph();printf("We'renowbackintextmode.\n");printf("Pressanykeytohalt:");getchO;return0;函數(shù)名:clreol功能:在文本窗口中清除字符到行末用法:voidclreol(void);程序例:Sinclude<conio.h>intmain(void)(clrscr();cprintf("ThefunctionCLREOLclearsallcharactersfromthe\r\n");cprintf("cursorpositiontotheendofthelinewithinthe\r\n);cprintf("currenttextwindow,withoutmovingthecursor.\r\n");cprintf("Pressanykeytocontinue...");gotoxy(14,4);getchO;clreol();getchO;return0;函數(shù)名:clrscr功能:清除文本模式窗口用法:voidclrscr(void);程序例:#include<conio.h>intmain(void)(inti;clrscr();for(i=0;i<20;i++)cprintf(級(jí)d\r\n",i);cprintf('\r\nPressanykeytoclearscreen");getchO;clrscr();cprintf("Thescreenhasbeencleared!");getchO;return0;函數(shù)名:coreleft功能:返回未使用內(nèi)存的大小用法:unsignedcoreleft(void);程序例:ttinclude<stdio.h>ttinclude<alloc.h>intmain(void)printf(zzThedifferencebetweenthehighestallocatedblockand\n，z);printf("thetopoftheheapis:%lubytes\n",(unsignedlong)coreleft());return0;)函數(shù)名:cos功能:余弦函數(shù)用法:doublecos(doublex);程序例:Sinclude<stdio.h>Sinclude<math.h>intmain(void)(doubleresult;doublex=0.5;result=cos(x);printf("Thecosineof%lfis%lf\n",x,result);return0;函數(shù)名:cosh功能:雙曲余弦函數(shù)用法:dlublecosh(doublex);程序例:ttinclude<stdio.h>ttinclude<math.h>intmain(void)(doubleresult;doublex=0.5;result=cosh(x);printf("Thehyperboiccosineof%lfis%lf\n",x,result);return0;函數(shù)名:country功能:返回與國(guó)家有關(guān)的信息用法:structCOUNTRY*country(intcountrycode,structcountry*country);程序例:ttinclude<dos.h>#include<stdio.h>#defineUSA0intmain(void)(structCOUNTRYcountry_info;country(USA,&country_info);printf(，zThecurrencysymbolfortheUSAis:%s\n,country_info.co_curr);return0;)函數(shù)名:cprintf功能:送格式化輸出至屏幕用法:intcprintf(constchar*format[,argument,程序例:ttinclude<conio.h>intmain(void)(/*clearthescreen*/clrscr();/*createatextwindow*/window(10,10,80,25);/*outputsometextinthewindow*/cprintf("Helloworld\r\n");/*waitforakey*/getchO;return0;函數(shù)名:cputs功能:寫字符到屏幕用法:voidcputs(constchar*string);程序例:#include<conio.h>intmain(void)(/*clearthescreen*/clrscr();/*createatextwindow*/window(10,10,80,25);/*outputsometextinthewindow*/cputs("Thisiswithinthewindow\r\n");/*waitforakey*/getchO;return0;函數(shù)名:_creatcreat功能:而建一個(gè)新文件或重寫ー個(gè)已存在的文件用法:intcreat(constchar"filename,intpermiss);程序例:#include<sys\stat.h>ttinclude<string.h>ttinclude<fcntl.h>#include<io.h>intmain(void){inthandle;charbuf[ll]="0123456789";/*changethedefaultfilemodefromtexttobinary*/_fmode=O_BINARY;/*createabinaryfileforreadingandwriting*/handle=creat("DUMMY.FIL",S_IREAD；SJWRITE);/*write10bytestothefile*/write(handle,buf,strlen(buf));/*closethefile*/close(handle);return0;函數(shù)名:creatnew功能:創(chuàng)建一個(gè)新文件用法:intcreatnew(constchar*filename,intattrib);程序例:#include<string.h>#include<stdio.h>#include<errno.h>#include<dos.h>Sinclude<io.h>intmain(void)(inthandle;charbuf[ll]="0123456789”;/*attempttocreateafilethatdoesn*talreadyexist*/handle=creatnew("DUMMY.FIL",0);if(handle==-1)printf("DUMMY.FILalreadyexists.\n");else(printf("DUMMY.FILsuccessfullycreated.\n");write(handle,buf,strlen(buf));close(handle);)return0;函數(shù)名:creattemp功能:創(chuàng)建一個(gè)新文件或重寫ー個(gè)已存在的文件用法:intcreattemp(constchar*filename,intattrib);程序例:ttinclude<string.h>Sinclude<stdio.h>#include<io.h>intmain(void)(inthandle;charpathname[128];strcpy(pathname,〃、、〃)；/*createauniquefileintherootdirectory*/handle=creattemp(pathname,0);printf(z，%swastheuniquefilecreated.\nz，,pathname);close(handle);return0;函數(shù)名:cscanf功能:從控制臺(tái)執(zhí)行格式化輸入用法:intcscanf(char*format[,argument,...]);程序例:#include<conio.h>intmain(void)(charstring[80];/*clearthescreen*/clrscr();/*Prompttheuserforinput*/cprintf(〃Enterastringwithnospaces:z，);/*readtheinput*/cscanf(zz%szz,string);/*displaywhatwasread*/cprintf(zz\r\nThestringenteredis:%s,string);return0;函數(shù)名:ctime功能:把日期和時(shí)間轉(zhuǎn)換為字符串用法:char*ctime(consttime_t*time);程序例:#include<stdio.h>ttinclude<time.h>intmain(void)(time_tt;time(&t);printf("Today'sdateandtime:%s\n",ctime(&t));return0;函數(shù)名:ctrlbrk功能:設(shè)置Ctrl-Break處理程序用法:voidctrlbrk(*fptr)(void);程序例:Sinclude<stdio.h>#include<dos.h>#defineABORT0intc_break(void)(printf("Control-Breakpressed.Programaborting...\n");return(ABORT);intmain(void){ctrlbrk(c_break);for(;;)(printf("Looping...PressくCtrl-Break〉toquit:\n");return0;函數(shù)D函數(shù)名:delay功能:將程序的執(zhí)行暫停一段時(shí)間(毫秒)用法:voiddelay(unsignedmilliseconds);程序例:/*Emitsa440-Hztonefor500milliseconds*/#include<dos.h>intmain(void)(sound(440);delay(500);nosoundO;return0;)函數(shù)名:delline功能:在文本窗口中刪去一行用法:voiddelline(void);程序例:Sinclude<conio.h>intmain(void)(clrscr();cprintf(z，ThefunctionDELLINEdeletes\thelinecontainingthe\r\n);cprintf(z，cursorandmovesalllines\belowitonelineup.\r\n");cprintf(Z/DELLINEoperateswithinthe\currentlyactivetext\r\n");cprintf(z/window.Pressanykeyto\continue...ノ;gotoxy(1,2);/*Movethecursortothesecondlineandfirstcolumn*/getchO;dellineO;getchO;return0;函數(shù)名:detectgraph功能:通過(guò)檢測(cè)硬件確定圖形驅(qū)動(dòng)程序和模式用法:voidfardetectgraph(intfar*graphdriver,intfar*graphmode);程序例:Sinclude<graphics.h>#include<stdlib.h>#include<stdio.h>#include<conio.h>/*namesofthevariouscardssupported*/char*dname[]={requestsdetection,〃aCGA”,“anMCGA〃,"anEGA","a64KEGA","amonochromeEGA","anIBM8514","aHerculesmonochrome","anAT&T6300PC","aVGA","anIBM3270PC")；intmain(void){/*returnsdetectedhardwareinfo.*/intgdriver,gmode,errorcode;/*detectgraphicshardwareavailable*/detectgraph(&gdriver,&gmode);/*readresultofdetectgraphcall*/errorcode=graphresult();if(errorcode!=grOk)/*anerroroccurred*/{printf("Graphicserror:%s\n",\grapherrormsg(errorcode));printf("Pressanykeytohalt:");getchO;exit(1);/*terminatewithanerrorcode*//*displaytheinformationdetected*/clrscr();printf(zzYouhave%svideodisplay\card.\n",dname[gdriver]);printf(z，Pressanykeytohalt:");getchO;return0;)函數(shù)名:difftime功能:計(jì)算兩個(gè)時(shí)刻之間的時(shí)間差用法:doubledifftime(time_ttime2,time_ttimel);程序例:#include<time.h>#include<stdio.h>ttinclude<dos.h>#include<conio.h>intmain(void)(time_tfirst,second;clrscr();first=time(NULL);/*Getssystemtime*/delay(2000);/*Waits2secs*/second=time(NULL);/*Getssystemtimeagain*/printf("Thedifferenceis:%f\seconds\n",difftime(second,first