函数名:?delay?

功??能:?将程序的执行暂停一段时间(毫秒)?

用??法:?void?delay(unsigned?milliseconds);?

程序例:?

/*?Emits?a?440-Hz?tone?for?500?milliseconds?*/?
#include?<dos.h>?
int?main(void)?
{?
???sound(440);?
???delay(500);?
???nosound();?
???return?0;?
}?
??
??

函数名:?delline?

功??能:?在文本窗口中删去一行?

用??法:?void?delline(void);?

程序例:?

#include?<conio.h>?
int?main(void)?
{?
???clrscr();?
???cprintf("The?function?DELLINE?deletes?\?
????the?line?containing?the\r\n");?
???cprintf("cursor?and?moves?all?lines?\?
????below?it?one?line?up.\r\n");?
???cprintf("DELLINE?operates?within?the?\?
????currently?active?text\r\n");?
???cprintf("window.??Press?any?key?to?\?
????continue?.?.?.");?
???gotoxy(1,2);??/*?Move?the?cursor?to?the?
??????second?line?and?first?column?*/?
???getch();?
???delline();?
???getch();?
???return?0;?
}?
??

函数名:?detectgraph?

功??能:?通过检测硬件确定图形驱动程序和模式?

用??法:?void?far?detectgraph(int?far?*graphdriver,?int?far?*graphmode);?

程序例:?

#include?<graphics.h>?
#include?<stdlib.h>?
#include?<stdio.h>?
#include?<conio.h>?
/*?names?of?the?various?cards?supported?*/?
char?*dname[]?=?{?"requests?detection",?
????"a?CGA",?
????"an?MCGA",?
????"an?EGA",?
????"a?64K?EGA",?
????"a?monochrome?EGA",?
????"an?IBM?8514",?
????"a?Hercules?monochrome",?
????"an?AT&T?6300?PC",?
????"a?VGA",?
????"an?IBM?3270?PC"?
??};?
int?main(void)?
{?
???/*?returns?detected?hardware?info.?*/?
???int?gdriver,?gmode,?errorcode;?
??/*?detect?graphics?hardware?available?*/?
???detectgraph(&gdriver,?&gmode);?
???/*?read?result?of?detectgraph?call?*/?
???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?*/?
???}?
???/*?display?the?information?detected?*/?
???clrscr();?
???printf("You?have?%s?video?display?\?
???card.\n",?dname[gdriver]);?
???printf("Press?any?key?to?halt:");?
???getch();?
???return?0;?
}?
??
??
??

函数名:?difftime?

功??能:?计算两个时刻之间的时间差?

用??法:?double?difftime(time_t?time2,?time_t?time1);?

程序例:?

#include?<time.h>?
#include?<stdio.h>?
#include?<dos.h>?
#include?<conio.h>?
int?main(void)?
{?
???time_t?first,?second;?
???clrscr();?
???first?=?time(NULL);??/*?Gets?system?
??????time?*/?
???delay(2000);?????????/*?Waits?2?secs?*/?
???second?=?time(NULL);?/*?Gets?system?time?
??????again?*/?
???printf("The?difference?is:?%f?\?
???seconds\n",difftime(second,first));?
???getch();?
???return?0;?
}?
??
??

函数名:?disable?

功??能:?屏蔽中断?

用??法:?void?disable(void);?

程序例:?

/***NOTE:?This?is?an?interrupt?service?
?routine.?You?cannot?compile?this?program?
?with?Test?Stack?Overflow?turned?on?and?
?get?an?executable?file?that?operates?
?correctly.?*/?
#include?<stdio.h>?
#include?<dos.h>?
#include?<conio.h>?
#define?INTR?0X1C????/*?The?clock?tick?
???interrupt?*/?
void?interrupt?(?*oldhandler)(void);?
int?count=0;?
void?interrupt?handler(void)?
{?
/*?disable?interrupts?during?the?handling?of?
???the?interrupt?*/?
???disable();?
/*?increase?the?global?counter?*/?
???count++;?
/*?reenable?interrupts?at?the?end?of?the?
???handler?*/?
???enable();?
/*?call?the?old?routine?*/?
???oldhandler();?
}?
int?main(void)?
{?
/*?save?the?old?interrupt?vector?*/?
???oldhandler?=?getvect(INTR);?
/*?install?the?new?interrupt?handler?*/?
???setvect(INTR,?handler);?
/*?loop?until?the?counter?exceeds?20?*/?
???while?(count?<?20)?
??????printf("count?is?%d\n",count);?
/*?reset?the?old?interrupt?handler?*/?
???setvect(INTR,?oldhandler);?
???return?0;?
}?

函数名:?div?

功??能:?将两个整数相除,?返回商和余数?

用??法:?div_t?(int?number,?int?denom);?

程序例:?

#include?<stdlib.h>?
#include?<stdio.h>?
div_t?x;?
int?main(void)?
{?
???x?=?div(10,3);?
???printf("10?div?3?=?%d?remainder?%d\n",?x.quot,?x.rem);?
???return?0;?
}?
??
??

函数名:?dosexterr?

功??能:?获取扩展DOS错误信息?

用??法:?int?dosexterr(struct?DOSERR?*dblkp);?

程序例:?

#include?<stdio.h>?
#include?<dos.h>?
int?main(void)?
{?
???FILE?*fp;?
???struct?DOSERROR?info;?
???fp?=?fopen("perror.dat","r");?
???if?(!fp)?perror("Unable?to?open?file?for?
?????reading");?
???dosexterr(&info);?
???printf("Extended?DOS?error?\?
???information:\n");?
???printf("???Extended?error:?\?
???%d\n",info.exterror);?
???printf("????????????Class:?\?
???%x\n",info.class);?
???printf("???????????Action:?\?
???%x\n",info.action);?
???printf("??????Error?Locus:?\?
???%x\n",info.locus);?
???return?0;?
}?
??
??

函数名:?dostounix?

功??能:?转换日期和时间为UNIX时间格式?

用??法:?long?dostounix(struct?date?*dateptr,?struct?time?*timeptr);?

程序例:?

?#include?<time.h>?
?#include?<stddef.h>?
?#include?<dos.h>?
?#include?<stdio.h>?
?int?main(void)?
?{?
????time_t?t;?
????struct?time?d_time;?
????struct?date?d_date;?
????struct?tm?*local;?
????getdate(&d_date);?
????gettime(&d_time);?
????t?=?dostounix(&d_date,?&d_time);?
????local?=?localtime(&t);?
????printf("Time?and?Date:?%s\n",?\?
????asctime(local));?
????return?0;?
}?
??
??

函数名:?drawpoly?

功??能:?画多边形?

用??法:?void?far?drawpoly(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?maxx,?maxy;?
???/*?our?polygon?array?*/?
???int?poly[10];?
???/*?initialize?graphics?and?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();?
???/*?terminate?with?an?error?code?*/?
??????exit(1);?
???}?
???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;?
???poly[6]?=?maxx?/?2;??/*?4th?*/?
???poly[7]?=?maxy?/?2;?
/*?
???drawpoly?doesn‘t?automatically?close?
???the?polygon,?so?we?close?it.?
*/?
???poly[8]?=?poly[0];?
???poly[9]?=?poly[1];?
???/*?draw?the?polygon?*/?
???drawpoly(5,?poly);?
???/*?clean?up?*/?
???getch();?
???closegraph();?
???return?0;?
}?
??
??

函数名:?dup?

功??能:?复制一个文件句柄?

用??法:?int?dup(int?handle);?

程序例:?

#include?<string.h>?
#include?<stdio.h>?
#include?<conio.h>?
#include?<io.h>?
void?flush(FILE?*stream);?
int?main(void)?
{?
???FILE?*fp;?
???char?msg[]?=?"This?is?a?test";?
???/*?create?a?file?*/?
???fp?=?fopen("DUMMY.FIL",?"w");?
???/*?write?some?data?to?the?file?*/?
???fwrite(msg,?strlen(msg),?1,?fp);?
???clrscr();?
???printf("Press?any?key?to?flush?\?
???DUMMY.FIL:");?
???getch();?
???/*?flush?the?data?to?DUMMY.FIL?without?
??????closing?it?*/?
???flush(fp);?
???printf("\nFile?was?flushed,?Press?any?\?
???key?to?quit:");?
???getch();?
???return?0;?
}?
void?flush(FILE?*stream)?
{?
???int?duphandle;?
???/*?flush?TC‘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:?dup2?

功??能:?复制文件句柄?

用??法:?int?dup2(int?oldhandle,?int?newhandle);?

程序例:?

#include?<sys\stat.h>?
#include?<string.h>?
#include?<fcntl.h>?
#include?<io.h>?
int?main(void)?
{?
???#define?STDOUT?1?
???int?nul,?oldstdout;?
???char?msg[]?=?"This?is?a?test";?
???/*?create?a?file?*/?
???nul?=?open("DUMMY.FIL",?O_CREAT?|?O_RDWR,?
??????S_IREAD?|?S_IWRITE);?
???/*?create?a?duplicate?handle?for?standard?
??????output?*/?
???oldstdout?=?dup(STDOUT);?
???/*?
??????redirect?standard?output?to?DUMMY.FIL?
??????by?duplicating?the?file?handle?onto?the?
??????file?handle?for?standard?output.?
???*/?
???dup2(nul,?STDOUT);?
???/*?close?the?handle?for?DUMMY.FIL?*/?
???close(nul);?
???/*?will?be?redirected?into?DUMMY.FIL?*/?
???write(STDOUT,?msg,?strlen(msg));?
???/*?restore?original?standard?output?
??????handle?*/?
???dup2(oldstdout,?STDOUT);?
???/*?close?duplicate?handle?for?STDOUT?*/?
???close(oldstdout);?
???return?0;?
}?