B开头的函数

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;   }