C language library functions (B-type letters)

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  
#include  
#include  
#include 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: %sn", 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{ 
/* 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  
#include  
#include  
#include 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: %sn", 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{ 
/* 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  
#include /* 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  

#include  
#include  
#include  
#include  
#include #define BUFLEN 80 int main(void) 
{ 
char buffer[BUFLEN]; 
int test; printf("Enter full pathname of a Directoryn"); 
gets(buffer); test = bdosptr(0x3B,buffer,0); 
if(test) 
{ 
printf("DOS error message: %dn", errno); 
/* See errno.h for error listings */ 
exit (1); 
} getcwd(buffer, BUFLEN); 
printf("The current directory is: %sn", 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  
#include #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  
#include int main(void) 
{ 
int result; 
char buffer[512]; printf("Testing to see if drive a: is readyn"); 
result = biosdisk(4,0,0,0,0,1,buffer); 
result &= 0x02; 
(result) ? (printf("Drive A: Readyn")) : 
(printf("Drive A: Not Readyn")); return 0; 
} 
函数名: biosequip 
功 能: 检查设备 
用 法: int biosequip(void); 
程序例: #include  
#include int main(void) 
{ 
int result; 
char buffer[512]; printf("Testing to see if drive a: is readyn"); 
result = biosdisk(4,0,0,0,0,1,buffer); 
result &= 0x02; 
(result) ? (printf("Drive A: Readyn")) : 
(printf("Drive A: Not Readyn")); 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  
#include  
#include #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("%#02xn", 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  
#include int main(void) 
{ 
int memory_size; memory_size = biosmemory(); /* returns value up to 640K */ 
printf("RAM size = %dKn",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  
#include  
#include 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 continuen"); 
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  
#include  
#include  
#include int main(void) 
{ 
long bios_time; clrscr(); 
cprintf("The number of clock ticks since midnight is:rn"); 
cprintf("The number of seconds since midnight is:rn"); 
cprintf("The number of minutes since midnight is:rn"); 
cprintf("The number of hours since midnight is:rn"); 
cprintf("rnPress 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;
}
Function name: brk
Function: Change data segment space allocation
Usage : int brk(void *endds);
Program example: #include
#include int main(void)
{
char *ptr; printf("Changing allocation with brk( )n");
ptr = malloc(1);
printf("Before brk() call: %lu bytes freen", coreleft());

brk(ptr+1000);
printf(" After brk( ) call: %lu bytes freen", coreleft());
return 0;
}
Function name: bsearch
Function: binary search
Usage: void *bsearch(const void *key, const void *base, size_t * nelem,
size_t width, int(*fcmp)(const void *, const *));
Program example: #include
#include #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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