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;}
