C语言库函数(F类字母)

C语言库函数(F类字母)


函数名: fabs
功 能: 返回浮点数的绝对值
用 法: double fabs(double x);
程序例:
#include <stdio.h>
#include <math.h>

int main(void)
{
float number = -1234.0;

printf("number: %f absolute value: %f\n",
number, fabs(number));
return 0;
}




函数名: farcalloc
功 能: 从远堆栈中申请空间
用 法: void far *farcalloc(unsigned long units, unsigned ling unitsz);
程序例:
#include <stdio.h>
#include <alloc.h>
#include <string.h>
#include <dos.h>

int main(void)
{
char far *fptr;
char *str = "Hello";

/* allocate memory for the far pointer */
fptr = farcalloc(10, sizeof(char));

/* copy "Hello" into allocated memory */
/*
Note: movedata is used because you
might be in a small data model, in
which case a normal string copy routine
can not be used since it assumes the
pointer size is near.
*/
movedata(FP_SEG(str), FP_OFF(str),
FP_SEG(fptr), FP_OFF(fptr),
strlen(str));

/* display string (note the F modifier) */
printf("Far string is: %Fs\n", fptr);

/* free the memory */
farfree(fptr);

return 0;
}




函数名: farcoreleft
功 能: 返回远堆中未作用存储区大小
用 法: long farcoreleft(void);
程序例:

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

int main(void)
{
printf("The difference between the\
highest allocated block in the\
far\n");
printf("heap and the top of the far heap\
is: %lu bytes\n", farcoreleft());

return 0;
}




函数名: farfree
功 能: 从远堆中释放一块
用 法: void farfree(void);
程序例:

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

int main(void)
{
char far *fptr;
char *str = "Hello";

/* allocate memory for the far pointer */
fptr = farcalloc(10, sizeof(char));

/* copy "Hello" into allocated memory */
/*
Note: movedata is used because you might be in a small data model,
in which case a normal string copy routine can't be used since it
assumes the pointer size is near.
*/
movedata(FP_SEG(str), FP_OFF(str),
FP_SEG(fptr), FP_OFF(fptr),
strlen(str));

/* display string (note the F modifier) */
printf("Far string is: %Fs\n", fptr);

/* free the memory */
farfree(fptr);

return 0;
}




函数名: farmalloc
功 能: 从远堆中分配存储块
用 法: void far *farmalloc(unsigned long size);
程序例:

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

int main(void)
{
char far *fptr;
char *str = "Hello";

/* allocate memory for the far pointer */
fptr = farmalloc(10);

/* copy "Hello" into allocated memory */
/*
Note: movedata is used because we might
be in a small data model, in which case
a normal string copy routine can not be
used since it assumes the pointer size
is near.
*/
movedata(FP_SEG(str), FP_OFF(str),
FP_SEG(fptr), FP_OFF(fptr),
strlen(str));

/* display string (note the F modifier) */
printf("Far string is: %Fs\n", fptr);

/* free the memory */
farfree(fptr);

return 0;
}




函数名: farrealloc
功 能: 调整远堆中的分配块
用 法: void far *farrealloc(void far *block, unsigned long newsize);
程序例:

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

int main(void)
{
char far *fptr;

fptr = farmalloc(10);
printf("First address: %Fp\n", fptr);
fptr = farrealloc(fptr,20);
printf("New address : %Fp\n", fptr);
farfree(fptr);
return 0;
}



函数名: fclose
功 能: 关闭一个流
用 法: int fclose(FILE *stream);
程序例:

#include <string.h>
#include <stdio.h>

int main(void)
{
FILE *fp;
char buf[11] = "0123456789";

/* create a file containing 10 bytes */
fp = fopen("DUMMY.FIL", "w");
fwrite(&buf, strlen(buf), 1, fp);

/* close the file */
fclose(fp);
return 0;
}




函数名: fcloseall
功 能: 关闭打开流
用 法: int fcloseall(void);
程序例:

#include <stdio.h>

int main(void)
{
int streams_closed;

/* open two streams */
fopen("DUMMY.ONE", "w");
fopen("DUMMY.TWO", "w");

/* close the open streams */
streams_closed = fcloseall();

if (streams_closed == EOF)
/* issue an error message */
perror("Error");
else
/* print result of fcloseall() function */
printf("%d streams were closed.\n", streams_closed);

return 0;
}



函数名: fcvt
功 能: 把一个浮点数转换为字符串
用 法: char *fcvt(double value, int ndigit, int *decpt, int *sign);

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