c语言函数--D

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; 
}