C语言函数_B起始_C语言教程

C语言函数_B起始_C语言教程

函数名: bar
功  能: 画一个二维条形图
用  法: void far bar(int left, int top, int right, int bottom);
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 midx, midy, i;

   /* 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();
      exit(1); /* terminate with an error code */
   }

   midx = getmaxx() / 2;
   midy = getmaxy() / 2;

   /* loop through the fill patterns */
   for (i=SOLID_FILL; i<USER_FILL; i++)
   {
      /* set the fill style */
      setfillstyle(i, getmaxcolor());

      /* draw the bar */
      bar(midx-50, midy-50, midx+50,
         midy+50);

      getch();
   }

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

函数名: bar3d
功  能: 画一个三维条形图
用  法: void far bar3d(int left, int top, int right, int bottom,
                       int depth, int topflag);
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 midx, midy, i;

   /* initialize graphics, 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();
      exit(1); /* terminate with error code */
   }

   midx = getmaxx() / 2;
   midy = getmaxy() / 2;

   /* loop through the fill patterns */
   for (i=EMPTY_FILL; i<USER_FILL; i++)
   {
      /* set the fill style */
      setfillstyle(i, getmaxcolor());

      /* draw the 3-d bar */
      bar3d(midx-50, midy-50, midx+50, midy+50, 10, 1);

      getch();
   }

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

函数名: bdos
功  能: DOS系统调用
用  法: int bdos(int dosfun, unsigned dosdx, unsigned dosal);
程序例:

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

/* Get current drive as 'A', 'B', ... */
char current_drive(void)
{
   char curdrive;

   /* Get current disk as 0, 1, ... */
   curdrive = bdos(0x19, 0, 0);
   return('A' + curdrive);
}

int main(void)
{
   printf("The current drive is %c:\n", current_drive());
   return 0;
}
 
 
 

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 <string.h>
#include <stdio.h>
#include <dir.h>
#include <dos.h>
#include <errno.h>
#include <stdlib.h>

#define  BUFLEN  80

int main(void)
{
   char  buffer[BUFLEN];
   int   test;

   printf("Enter full pathname of a directory\n");
   gets(buffer);

   test = bdosptr(0x3B,buffer,0);
      if(test)
      {
  printf("DOS error message: %d\n", errno);
  /* See errno.h for error listings */
  exit (1);
      }

   getcwd(buffer, BUFLEN);
   printf("The current directory is: %s\n", buffer);

   return 0;
}
 
 
 

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 <bios.h>
#include <conio.h>

#define COM1       0
#define DATA_READY 0x100
#define TRUE       1
#define FALSE      0

#define SETTINGS ( 0x80 | 0x02 | 0x00 | 0x00)

int main(void)
{
   int in, out, status, DONE = FALSE;

   bioscom(0, SETTINGS, COM1);
   cprintf("... BIOSCOM [ESC] to exit ...\n");
   while (!DONE)
   {
      status = bioscom(3, 0, COM1);
      if (status & DATA_READY)
  if ((out = bioscom(2, 0, COM1) & 0x7F) != 0)
     putch(out);
  if (kbhit())
  {
     if ((in = getch()) == '\x1B')
        DONE = TRUE;
     bioscom(1, in, COM1);
  }
   }
   return 0;
}
 
 
 

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 <bios.h>
#include <stdio.h>

int main(void)
{
   int result;
   char buffer[512];

   printf("Testing to see if drive a: is ready\n");
   result = biosdisk(4,0,0,0,0,1,buffer);
   result &= 0x02;
   (result) ? (printf("Drive A: Ready\n")) :
       (printf("Drive A: Not Ready\n"));

   return 0;
}
 
 
 

函数名: biosequip
功  能: 检查设备
用  法: int biosequip(void);
程序例:

#include <bios.h>
#include <stdio.h>

int main(void)
{
   int result;
   char buffer[512];

   printf("Testing to see if drive a: is ready\n");
   result = biosdisk(4,0,0,0,0,1,buffer);
   result &= 0x02;
   (result) ? (printf("Drive A: Ready\n")) :
       (printf("Drive A: Not Ready\n"));

   return 0;
}
 
 
 

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 <stdio.h>
#include <bios.h>
#include <ctype.h>

#define RIGHT  0x01
#define LEFT   0x02
#define CTRL   0x04
#define ALT    0x08

int main(void)
{
   int key, modifiers;

   /* function 1 returns 0 until a key is pressed */
   while (bioskey(1) == 0);

   /* function 0 returns the key that is waiting */
   key = bioskey(0);

   /* use function 2 to determine if shift keys were used */
   modifiers = bioskey(2);
   if (modifiers)
   {
      printf("[");
      if (modifiers & RIGHT) printf("RIGHT");
      if (modifiers & LEFT)  printf("LEFT");
      if (modifiers & CTRL)  printf("CTRL");
      if (modifiers & ALT)   printf("ALT");
      printf("]");
   }
   /* print out the character read */
   if (isalnum(key & 0xFF))
      printf("'%c'\n", key);
   else
      printf("%#02x\n", key);
   return 0;
}
 
 

函数名: biosmemory
功  能: 返回存储块大小
用  法:int biosmemory(void);
程序例:

#include <stdio.h>
#include <bios.h>

int main(void)
{
   int memory_size;

   memory_size = biosmemory();  /* returns value up to 640K */
   printf("RAM size = %dK\n",memory_size);
   return 0;
}
 
 
 

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 <stdio.h>
#include <conio.h>
#include <bios.h>

int main(void)
{
   #define STATUS  2    /* printer status command */
   #define PORTNUM 0    /* port number for LPT1 */

   int status, abyte=0;

   printf("Please turn off your printer.  Press any key to continue\n");
   getch();
   status = biosprint(STATUS, abyte, PORTNUM);
   if (status & 0x01)
      printf("Device time out.\n");
   if (status & 0x08)
      printf("I/O error.\n");

   if (status & 0x10)
      printf("Selected.\n");
   if (status & 0x20)
      printf("Out of paper.\n");

   if (status & 0x40)
      printf("Acknowledge.\n");
   if (status & 0x80)
      printf("Not busy.\n");

   return 0;
}
 
 
 

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 <stdio.h>
#include <bios.h>
#include <time.h>
#include <conio.h>

int main(void)
{
   long bios_time;

   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);

      gotoxy(50, 1);
      cprintf("%lu", bios_time);

      gotoxy(50, 2);
      cprintf("%.4f", bios_time / CLK_TCK);

      gotoxy(50, 3);
      cprintf("%.4f", bios_time / CLK_TCK / 60);

      gotoxy(50, 4);
      cprintf("%.4f", bios_time / CLK_TCK / 3600);
   }
   return 0;
}
 
 
 

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 <stdio.h>
#include <alloc.h>

int main(void)
{
   char *ptr;

   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;
}
 
 
 

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

#define NELEMS(arr) (sizeof(arr) / sizeof(arr[0]))

int numarray[] = {123, 145, 512, 627, 800, 933};

int numeric (const int *p1, const int *p2)
{
   return(*p1 - *p2);
}

int lookup(int key)
{
   int *itemptr;

   /* The cast of (int(*)(const void *,const void*))
      is needed to avoid a type mismatch error at
      compile time */
   itemptr = bsearch (&key, numarray, NELEMS(numarray),
      sizeof(int), (int(*)(const void *,const void *))numeric);
   return (itemptr != NULL);
}

int main(void)
{
   if (lookup(512))
      printf("512 is in the table.\n");
   else
      printf("512 isn't in the table.\n");

   return 0;
}

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