C语言的函数!

内财数模协会

<>函数名: linerel
功  能: 从当前位置点(CP)到与CP有一给定相对距离的点画一直线
用  法: void far linerel(int dx, int dy);
程序例: <>#include &lt;graphics.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;stdio.h&gt;
#include &lt;conio.h&gt; <>int main(void)
{
   /* request auto detection */
   int gdriver = DETECT, gmode, errorcode;
   char msg[80]; <P>   /* initialize graphics and local variables */
   initgraph(&amp;gdriver, &amp;gmode, ""); <P>   /* read result of initialization */
   errorcode = graphresult();
   if (errorcode != grOk)
   {
      printf("Graphics error: %s\n",
  grapherrormsg(errorcode));
      printf("Press any key to halt:");
      getch();
      exit(1);
   } <P>   /* move the C.P. to location (20, 30) */
   moveto(20, 30); <P>   /* create and output a
      message at (20, 30) */
   sprintf(msg, " (%d, %d)", getx(), gety());
   outtextxy(20, 30, msg); <P>   /* draw a line to a point a relative
      distance away from the current
      value of C.P.   */
   linerel(100, 100); <P>   /* create and output a message at C.P. */
   sprintf(msg, " (%d, %d)", getx(), gety());
   outtext(msg); <P>   /* clean up */
   getch();
   closegraph();
   return 0;
}
</P>

内财数模协会

<>函数名: localtime
功  能: 把日期和时间转变为结构
用  法: struct tm *localtime(long *clock);
程序例: <>#include &lt;time.h&gt;
#include &lt;stdio.h&gt;
#include &lt;dos.h&gt; <>int main(void)
{
   time_t timer;
   struct tm *tblock; <P>   /* gets time of day */
   timer = time(NULL); <P>   /* converts date/time to a structure */
   tblock = localtime(&amp;timer); <P>   printf("Local time is: %s", asctime(tblock)); <P>   return 0;
}
</P>

内财数模协会

<>函数名: lock
功  能: 设置文件共享锁
用  法: int lock(int handle, long offset, long length);
程序例: <>#include &lt;io.h&gt;
#include &lt;fcntl.h&gt;
#include &lt;sys\stat.h&gt;
#include &lt;process.h&gt;
#include &lt;share.h&gt;
#include &lt;stdio.h&gt; <>int main(void)
{
   int handle, status;
   long length; <P>   /* Must have DOS Share.exe loaded for */
   /* file locking to function properly */ <P>   handle = sopen("c:\\autoexec.bat",
      O_RDONLY,SH_DENYNO,S_IREAD); <P>   if (handle &lt; 0)
   {
      printf("sopen failed\n");
      exit(1);
   } <P>   length = filelength(handle);
   status = lock(handle,0L,length/2); <P>   if (status == 0)
      printf("lock succeeded\n");
   else
      printf("lock failed\n"); <P>   status = unlock(handle,0L,length/2); <P>   if (status == 0)
      printf("unlock succeeded\n");
   else
      printf("unlock failed\n"); <P>   close(handle);
   return 0;
}
  
</P>

内财数模协会

<>函数名: log
功  能: 对数函数ln(x)
用  法: double log(double x);
程序例: <>#include &lt;math.h&gt;
#include &lt;stdio.h&gt; <>int main(void)
{
   double result;
   double x = 8.6872; <P>   result = log(x);
   printf("The natural log of %lf is %lf\n", x, result); <P>   return 0;
}
  
  </P>

内财数模协会

<>函数名: log10
功  能: 对数函数log
用  法: double log10(double x);
程序例: <>#include &lt;math.h&gt;
#include &lt;stdio.h&gt; <>int main(void)
{
   double result;
   double x = 800.6872; <P>   result = log10(x);
   printf("The common log of %lf is %lf\n", x, result); <P>   return 0;
}
</P>

内财数模协会

<>函数名: longjump
功  能: 执行非局部转移
用  法: void longjump(jmp_buf env, int val);
程序例: <>#include &lt;stdio.h&gt;
#include &lt;setjmp.h&gt;
#include &lt;stdlib.h&gt; <>void subroutine(jmp_buf); <P>int main(void)
{ <P>   int value;
   jmp_buf jumper; <P>   value = setjmp(jumper);
   if (value != 0)
   {
      printf("Longjmp with value %d\n", value);
      exit(value);
   }
   printf("About to call subroutine ... \n");
   subroutine(jumper); <P>   return 0;
} <P>void subroutine(jmp_buf jumper)
{
   longjmp(jumper,1);
}
  
</P>

内财数模协会

<>函数名: lowvideo
功  能: 选择低亮度字符
用  法: void lowvideo(void);
程序例: <>#include &lt;conio.h&gt; <>int main(void)
{
   clrscr(); <P>   highvideo();
   cprintf("High Intesity Text\r\n");
   lowvideo();
   gotoxy(1,2);
   cprintf("Low Intensity Text\r\n"); <P>   return 0;
}
  
</P>

内财数模协会

<>函数名: lrotl, _lrotl
功  能: 将无符号长整型数向左循环移位
用  法: unsigned long lrotl(unsigned long lvalue, int count);
unsigned long _lrotl(unsigned long lvalue, int count);
程序例: <>/* lrotl example */
#include &lt;stdlib.h&gt;
#include &lt;stdio.h&gt; <>int main(void)
{
   unsigned long result;
   unsigned long value = 100; <P>   result = _lrotl(value,1);
   printf("The value %lu rotated left one bit is: %lu\n", value, result); <P>   return 0;
}
  
</P>

内财数模协会

<>函数名: lsearch
功  能: 线性搜索
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 &lt;stdio.h&gt;
#include &lt;stdlib.h&gt; <>int compare(int *x, int *y)
{
   return( *x - *y );
} <P>int main(void)
{
   int array[5] = {35, 87, 46, 99, 12};
   size_t nelem = 5;
   int key;
   int *result; <P>   key = 99;
   result = lfind(&amp;key, array, &amp;nelem,
               sizeof(int), (int(*)(const void *,const void *))compare);
   if (result)
      printf("Number %d found\n",key);
   else
      printf("Number %d not found\n",key); <P>   return 0;
}
</P>

内财数模协会

<>函数名: lseek
功  能: 移动文件读/写指针
用  法: long lseek(int handle, long offset, int fromwhere);
程序例: <>#include &lt;sys\stat.h&gt;
#include &lt;string.h&gt;
#include &lt;stdio.h&gt;
#include &lt;fcntl.h&gt;
#include &lt;io.h&gt; <>int main(void)
{
   int handle;
   char msg[] = "This is a test";
   char ch; <P>   /* create a file */
   handle = open("TEST.$$$", O_CREAT | O_RDWR, S_IREAD | S_IWRITE); <P>   /* write some data to the file */
   write(handle, msg, strlen(msg)); <P>   /* seek to the begining of the file */
   lseek(handle, 0L, SEEK_SET); <P>   /* reads chars from the file until we hit EOF */
   do
   {
      read(handle, &amp;ch, 1);
      printf("%c", ch);
   }  while (!eof(handle)); <P>   close(handle);
   return 0;
}
  </P>