fd.txt

c语言编程宝典

   
   
   
   fd
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;
}
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