函數(shù)名: labs
功  能: 取長整型絕對值
用  法: long labs(long n);
程序例:

#include <stdio.h>
#include <math.h>

int main(void)
{
   long result;
   long x = -12345678L;

   result= labs(x);
   printf(“number: %ld abs value: %ldn”,
      x, result);

   return 0;
}
 
 
 

函數(shù)名: ldexp
功  能: 計(jì)算value*2的冪
用  法: double ldexp(double value, int exp);
程序例:

#include <stdio.h>
#include <math.h>

int main(void)
{
   double value;
   double x = 2;

   /* ldexp raises 2 by a power of 3
      then multiplies the result by 2   */
   value = ldexp(x,3);
   printf(“The ldexp value is: %lfn”,
      value);

   return 0;
}
 
 

函數(shù)名: ldiv
功  能: 兩個(gè)長整型數(shù)相除, 返回商和余數(shù)
用  法: ldiv_t ldiv(long lnumer, long ldenom);
程序例:

/* ldiv example */

#include <stdlib.h>
#include <stdio.h>

int main(void)
{
   ldiv_t lx;

   lx = ldiv(100000L, 30000L);
   printf(“100000 div 30000 = %ld remainder %ldn”, lx.quot, lx.rem);
   return 0;
}
 
 
 

函數(shù)名: lfind
功  能: 執(zhí)行線性搜索
用  法: void *lfind(void *key, void *base, int *nelem, int width,
      int (*fcmp)());
程序例:

#include <stdio.h>
#include <stdlib.h>

int compare(int *x, int *y)
{
   return( *x – *y );
}

int main(void)
{
   int array[5] = {35, 87, 46, 99, 12};
   size_t nelem = 5;
   int key;
   int *result;

   key = 99;
   result = lfind(&key, array, &nelem,
        sizeof(int), (int(*)(const void *,const void *))compare);
   if (result)
      printf(“Number %d foundn”,key);
   else
      printf(“Number %d not foundn”,key);

   return 0;
}
 
 

函數(shù)名: line
功  能: 在指定兩點(diǎn)間畫一直線
用  法: void far line(int x0, int y0, int x1, int y1);
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 xmax, ymax;

   /* initialize graphics and local variables */
   initgraph(&gdriver, &gmode, “”);

   /* read result of initialization */
   errorcode = graphresult();
   /* an error occurred */
   if (errorcode != grOk)
   {
      printf(“Graphics error: %sn”,
             grapherrormsg(errorcode));
      printf(“Press any key to halt:”);
      getch();
      exit(1);
   }

   setcolor(getmaxcolor());
   xmax = getmaxx();
   ymax = getmaxy();

   /* draw a diagonal line */
   line(0, 0, xmax, ymax);

   /* clean up */
   getch();
   closegraph();
   return 0;
}
 
 

函數(shù)名: linerel
功  能: 從當(dāng)前位置點(diǎn)(CP)到與CP有一給定相對距離的點(diǎn)畫一直線
用  法: void far linerel(int dx, int dy);
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;
   char msg[80];

   /* initialize graphics and local variables */
   initgraph(&gdriver, &gmode, “”);

   /* read result of initialization */
   errorcode = graphresult();
   if (errorcode != grOk)
   {
      printf(“Graphics error: %sn”,
  grapherrormsg(errorcode));
      printf(“Press any key to halt:”);
      getch();
      exit(1);
   }

   /* move the C.P. to location (20, 30) */
   moveto(20, 30);

   /* create and output a
      message at (20, 30) */
   sprintf(msg, ” (%d, %d)”, getx(), gety());
   outtextxy(20, 30, msg);

   /* draw a line to a point a relative
      distance away from the current
      value of C.P.   */
   linerel(100, 100);

   /* create and output a message at C.P. */
   sprintf(msg, ” (%d, %d)”, getx(), gety());
   outtext(msg);

   /* clean up */
   getch();
   closegraph();
   return 0;
}
 

函數(shù)名: localtime
功  能: 把日期和時(shí)間轉(zhuǎn)變?yōu)榻Y(jié)構(gòu)
用  法: struct tm *localtime(long *clock);
程序例:

#include <time.h>
#include <stdio.h>
#include <dos.h>

int main(void)
{
   time_t timer;
   struct tm *tblock;

   /* gets time of day */
   timer = time(NULL);

   /* converts date/time to a structure */
   tblock = localtime(&timer);

   printf(“Local time is: %s”, asctime(tblock));

   return 0;
}
 
 
 

函數(shù)名: lock
功  能: 設(shè)置文件共享鎖
用  法: int lock(int handle, long offset, long length);
程序例:

#include <io.h>
#include <fcntl.h>
#include <sysstat.h>
#include <process.h>
#include <share.h>
#include <stdio.h>

int main(void)
{
   int handle, status;
   long length;

   /* Must have DOS Share.exe loaded for */
   /* file locking to function properly */

   handle = sopen(“c:\autoexec.bat”,
      O_RDONLY,SH_DENYNO,S_IREAD);

   if (handle < 0)
   {
      printf(“sopen failedn”);
      exit(1);
   }

   length = filelength(handle);
   status = lock(handle,0L,length/2);

   if (status == 0)
      printf(“lock succeededn”);
   else
      printf(“lock failedn”);

   status = unlock(handle,0L,length/2);

   if (status == 0)
      printf(“unlock succeededn”);
   else
      printf(“unlock failedn”);

   close(handle);
   return 0;
}
 
 

函數(shù)名: log
功  能: 對數(shù)函數(shù)ln(x)
用  法: double log(double x);
程序例:

#include <math.h>
#include <stdio.h>

int main(void)
{
   double result;
   double x = 8.6872;

   result = log(x);
   printf(“The natural log of %lf is %lfn”, x, result);

   return 0;
}
 
 

函數(shù)名: log10
功  能: 對數(shù)函數(shù)log
用  法: double log10(double x);
程序例:

#include <math.h>
#include <stdio.h>

int main(void)
{
   double result;
   double x = 800.6872;

   result = log10(x);
   printf(“The common log of %lf is %lfn”, x, result);

   return 0;
}
 
 
 

函數(shù)名: longjump
功  能: 執(zhí)行非局部轉(zhuǎn)移
用  法: void longjump(jmp_buf env, int val);
程序例:

#include <stdio.h>
#include <setjmp.h>
#include <stdlib.h>

void subroutine(jmp_buf);

int main(void)
{

   int value;
   jmp_buf jumper;

   value = setjmp(jumper);
   if (value != 0)
   {
      printf(“Longjmp with value %dn”, value);
      exit(value);
   }
   printf(“About to call subroutine … n”);
   subroutine(jumper);

   return 0;
}

void subroutine(jmp_buf jumper)
{
   longjmp(jumper,1);
}
 
 
 

函數(shù)名: lowvideo
功  能: 選擇低亮度字符
用  法: void lowvideo(void);
程序例:

#include <conio.h>

int main(void)
{
   clrscr();

   highvideo();
   cprintf(“High Intesity Textrn”);
   lowvideo();
   gotoxy(1,2);
   cprintf(“Low Intensity Textrn”);

   return 0;
}
 
 
 

函數(shù)名: lrotl, _lrotl
功  能: 將無符號長整型數(shù)向左循環(huán)移位
用  法: unsigned long lrotl(unsigned long lvalue, int count);
 unsigned long _lrotl(unsigned long lvalue, int count);
程序例:

/* lrotl example */
#include <stdlib.h>
#include <stdio.h>

int main(void)
{
   unsigned long result;
   unsigned long value = 100;

   result = _lrotl(value,1);
   printf(“The value %lu rotated left one bit is: %lun”, value, result);

   return 0;
}
 
 

函數(shù)名: lsearch
功  能: 線性搜索
用  法: void *lsearch(const void *key, void *base, size_t *nelem,
       size_t width, int (*fcmp)(const void *, const void *));
程序例:

#include <stdio.h>
#include <stdlib.h>

int compare(int *x, int *y)
{
   return( *x – *y );
}

int main(void)
{
   int array[5] = {35, 87, 46, 99, 12};
   size_t nelem = 5;
   int key;
   int *result;

   key = 99;
   result = lfind(&key, array, &nelem,
               sizeof(int), (int(*)(const void *,const void *))compare);
   if (result)
      printf(“Number %d foundn”,key);
   else
      printf(“Number %d not foundn”,key);

   return 0;
}
 
 
 

函數(shù)名: lseek
功  能: 移動(dòng)文件讀/寫指針
用  法: long lseek(int handle, long offset, int fromwhere);
程序例:

#include <sysstat.h>
#include <string.h>
#include <stdio.h>
#include <fcntl.h>
#include <io.h>

int main(void)
{
   int handle;
   char msg[] = “This is a test”;
   char ch;

   /* create a file */
   handle = open(“TEST.$$$”, O_CREAT | O_RDWR, S_IREAD | S_IWRITE);

   /* write some data to the file */
   write(handle, msg, strlen(msg));

   /* seek to the begining of the file */
   lseek(handle, 0L, SEEK_SET);

   /* reads chars from the file until we hit EOF */
   do
   {
      read(handle, &ch, 1);
      printf(“%c”, ch);
   }  while (!eof(handle));

   close(handle);
   return 0;
}