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C语言的函数!

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 楼主| 发表于 2004-5-8 17:14:42 | 显示全部楼层
<>函数名: bdosptr
功  能: DOS系统调用
用  法: int bdosptr(int dosfun, void *argument, unsigned dosal);
程序例: <>#include &lt;string.h&gt;
#include &lt;stdio.h&gt;
#include &lt;dir.h&gt;
#include &lt;dos.h&gt;
#include &lt;errno.h&gt;
#include &lt;stdlib.h&gt; <>#define  BUFLEN  80 <P>int main(void)
{
   char  buffer[BUFLEN];
   int   test; <P>   printf("Enter full pathname of a directory\n");
   gets(buffer); <P>   test = bdosptr(0x3B,buffer,0);
      if(test)
      {
  printf("DOS error message: %d\n", errno);
  /* See errno.h for error listings */
  exit (1);
      } <P>   getcwd(buffer, BUFLEN);
   printf("The current directory is: %s\n", buffer); <P>   return 0;
}
  
  
  </P>
 楼主| 发表于 2004-5-8 17:14:59 | 显示全部楼层
<>函数名: bioscom
功  能: 串行I/O通信
用  法: int bioscom(int cmd, char abyte, int port);
程序例: <>#include &lt;bios.h&gt;
#include &lt;conio.h&gt; <>#define COM1       0
#define DATA_READY 0x100
#define TRUE       1
#define FALSE      0 <P>#define SETTINGS ( 0x80 | 0x02 | 0x00 | 0x00) <P>int main(void)
{
   int in, out, status, DONE = FALSE; <P>   bioscom(0, SETTINGS, COM1);
   cprintf("... BIOSCOM [ESC] to exit ...\n");
   while (!DONE)
   {
      status = bioscom(3, 0, COM1);
      if (status &amp; DATA_READY)
  if ((out = bioscom(2, 0, COM1) &amp; 0x7F) != 0)
     putch(out);
  if (kbhit())
  {
     if ((in = getch()) == '\x1B')
        DONE = TRUE;
     bioscom(1, in, COM1);
  }
   }
   return 0;
}
  
  
  </P>
 楼主| 发表于 2004-5-8 17:15:14 | 显示全部楼层
<>函数名: biosdisk
功  能: 软硬盘I/O
用  法: int biosdisk(int cmd, int drive, int head, int track, int sector
       int nsects, void *buffer);
程序例: <>#include &lt;bios.h&gt;
#include &lt;stdio.h&gt; <>int main(void)
{
   int result;
   char buffer[512]; <P>   printf("Testing to see if drive a: is ready\n");
   result = biosdisk(4,0,0,0,0,1,buffer);
   result &amp;= 0x02;
   (result) ? (printf("Drive A: Ready\n")) :
       (printf("Drive A: Not Ready\n")); <P>   return 0;
}
  
  
  </P>
 楼主| 发表于 2004-5-8 17:15:30 | 显示全部楼层
<>函数名: biosequip
功  能: 检查设备
用  法: int biosequip(void);
程序例: <>#include &lt;bios.h&gt;
#include &lt;stdio.h&gt; <>int main(void)
{
   int result;
   char buffer[512]; <P>   printf("Testing to see if drive a: is ready\n");
   result = biosdisk(4,0,0,0,0,1,buffer);
   result &amp;= 0x02;
   (result) ? (printf("Drive A: Ready\n")) :
       (printf("Drive A: Not Ready\n")); <P>   return 0;
}
  
  
  </P>
 楼主| 发表于 2004-5-8 17:15:47 | 显示全部楼层
<>函数名: bioskey
功  能: 直接使用BIOS服务的键盘接口
用  法: int bioskey(int cmd);
程序例: <>#include &lt;stdio.h&gt;
#include &lt;bios.h&gt;
#include &lt;ctype.h&gt; <>#define RIGHT  0x01
#define LEFT   0x02
#define CTRL   0x04
#define ALT    0x08 <P>int main(void)
{
   int key, modifiers; <P>   /* function 1 returns 0 until a key is pressed */
   while (bioskey(1) == 0); <P>   /* function 0 returns the key that is waiting */
   key = bioskey(0); <P>   /* use function 2 to determine if shift keys were used */
   modifiers = bioskey(2);
   if (modifiers)
   {
      printf("[");
      if (modifiers &amp; RIGHT) printf("RIGHT");
      if (modifiers &amp; LEFT)  printf("LEFT");
      if (modifiers &amp; CTRL)  printf("CTRL");
      if (modifiers &amp; ALT)   printf("ALT");
      printf("]");
   }
   /* print out the character read */
   if (isalnum(key &amp; 0xFF))
      printf("'%c'\n", key);
   else
      printf("%#02x\n", key);
   return 0;
}
  
  </P>
 楼主| 发表于 2004-5-8 17:16:02 | 显示全部楼层
<>函数名: biosmemory
功  能: 返回存储块大小
用  法:int biosmemory(void);
程序例: <>#include &lt;stdio.h&gt;
#include &lt;bios.h&gt; <>int main(void)
{
   int memory_size; <P>   memory_size = biosmemory();  /* returns value up to 640K */
   printf("RAM size = %dK\n",memory_size);
   return 0;
}
  
  
  </P>
 楼主| 发表于 2004-5-8 17:16:18 | 显示全部楼层
<>函数名: biosprint
功  能: 直接使用BIOS服务的打印机I/O
用  法: int biosprint(int cmd, int byte, int port);
程序例: <>#include &lt;stdio.h&gt;
#include &lt;conio.h&gt;
#include &lt;bios.h&gt; <>int main(void)
{
   #define STATUS  2    /* printer status command */
   #define PORTNUM 0    /* port number for LPT1 */ <P>   int status, abyte=0; <P>   printf("Please turn off your printer.  Press any key to continue\n");
   getch();
   status = biosprint(STATUS, abyte, PORTNUM);
   if (status &amp; 0x01)
      printf("Device time out.\n");
   if (status &amp; 0x08)
      printf("I/O error.\n"); <P>   if (status &amp; 0x10)
      printf("Selected.\n");
   if (status &amp; 0x20)
      printf("Out of paper.\n"); <P>   if (status &amp; 0x40)
      printf("Acknowledge.\n");
   if (status &amp; 0x80)
      printf("Not busy.\n"); <P>   return 0;
}
  
  
  </P>
 楼主| 发表于 2004-5-8 17:16:34 | 显示全部楼层
<>函数名: biostime
功  能: 读取或设置BIOS时间
用  法: long biostime(int cmd, long newtime);
程序例: <>#include &lt;stdio.h&gt;
#include &lt;bios.h&gt;
#include &lt;time.h&gt;
#include &lt;conio.h&gt; <>int main(void)
{
   long bios_time; <P>   clrscr();
   cprintf("The number of clock ticks since midnight is:\r\n");
   cprintf("The number of seconds since midnight is:\r\n");
   cprintf("The number of minutes since midnight is:\r\n");
   cprintf("The number of hours since midnight is:\r\n");
   cprintf("\r\nPress any key to quit:");
   while(!kbhit())
   {
      bios_time = biostime(0, 0L); <P>      gotoxy(50, 1);
      cprintf("%lu", bios_time); <P>      gotoxy(50, 2);
      cprintf("%.4f", bios_time / CLK_TCK); <P>      gotoxy(50, 3);
      cprintf("%.4f", bios_time / CLK_TCK / 60); <P>      gotoxy(50, 4);
      cprintf("%.4f", bios_time / CLK_TCK / 3600);
   }
   return 0;
}
  
  
  </P>
 楼主| 发表于 2004-5-8 17:16:47 | 显示全部楼层
<>函数名: brk
功  能: 改变数据段空间分配
用  法: int brk(void *endds);
程序例: <>#include &lt;stdio.h&gt;
#include &lt;alloc.h&gt; <>int main(void)
{
   char *ptr; <P>   printf("Changing allocation with brk()\n");
   ptr = malloc(1);
   printf("Before brk() call: %lu bytes free\n", coreleft());
   brk(ptr+1000);
   printf(" After brk() call: %lu bytes free\n", coreleft());
   return 0;
}
  
  
  </P>
 楼主| 发表于 2004-5-8 17:17:03 | 显示全部楼层
<>函数名: bsearch
功  能: 二分法搜索
用  法: void *bsearch(const void *key, const void *base, size_t *nelem,
        size_t width, int(*fcmp)(const void *, const *));
程序例: <>#include &lt;stdlib.h&gt;
#include &lt;stdio.h&gt; <>#define NELEMS(arr) (sizeof(arr) / sizeof(arr[0])) <P>int numarray[] = {123, 145, 512, 627, 800, 933}; <P>int numeric (const int *p1, const int *p2)
{
   return(*p1 - *p2);
} <P>int lookup(int key)
{
   int *itemptr; <P>   /* The cast of (int(*)(const void *,const void*))
      is needed to avoid a type mismatch error at
      compile time */
   itemptr = bsearch (&amp;key, numarray, NELEMS(numarray),
      sizeof(int), (int(*)(const void *,const void *))numeric);
   return (itemptr != NULL);
} <P>int main(void)
{
   if (lookup(512))
      printf("512 is in the table.\n");
   else
      printf("512 isn't in the table.\n"); <P>   return 0;
}
  </P>
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