See Also

perror(3)

21 July 1996

exit

exit—Causes normal program termination

Synopsis

#include <stdlib.h>
void exit(int status);

Description

The exit() function causes normal program termination, and the value of status is returned to the parent. All functions registered with atexit() and on exit() are called in the reverse order of their registration, and all open streams are flushed and closed.

Return Value

The exit() function does not return.

Conforms To

SVID 3, POSIX, BSD 4.3, ISO 9899

See Also

_exit(2), atexit(3), on_exit(3)

GNU, 2 April 1993

exp, log, log10, pow

exp, log, log10, pow—Exponential, logarithmic, and power functions

Synopsis

#include <math.h>
double exp(double x);

double log(double x);
double log10(double x);
double pow(double x, double y);

Description

The exp() function returns the value of e (the base of natural logarithms) raised to the power of x.

The log() function returns the natural logarithm of x.

The log10() function returns the base-10 logarithm of x.

The pow() function returns the value of x raised to the power of y.

Errors

The log() and log10() functions can return the following errors:

EDOM     The argument x is negative.
ERANGE     The argument x is 0. The log of 0 is not defined.

The pow() function can return the following error:

EDOM     The argument x is negative and y is not an integral value. This would result in a complex number.

CONFORMS TO

SVID 3, POSIX, BSD 4.3, ISO 9899

SEE ALSO

sqrt(3), cbrt(3)

GNU June 16, 1993

expm1, log1p

expm1, log1p—Exponential minus 1, logarithm of 1 plus argument

SYNOPSIS

#include <math.h>
double expm1 (double x);
double log1p (double x);

expm1(x) returns a value equivalent to exp (x)_1. It is computed in a way that is accurate even if the value of x is near 0—a case where exp (x)_1 would be inaccurate due to subtraction of two numbers that are nearly equal.

log1p(x) returns a value equivalent to log (1 + x). It is computed in a way that is accurate even if the value of x is near 0.

CONFORMS TO

BSD

SEE ALSO

exp(3), log(3)

GNU, 16 September 1995

fabs

Fabs—Absolute value of floating-point number

SYNOPSIS

#include <math.h>
double fabs(double x);

DESCRIPTION

The fabs() function returns the absolute value of the floating-point number x.

CONFORMS TO

SVID 3, POSIX, BSD 4.3, ISO 9899

SEE ALSO

abs(3), ceil(3), floor(3), labs(3), rint(3)

25 June 1993

fclose

fclose—Closes a stream

SYNOPSIS

#include <stdio.h>
int fclose(FILE *stream);

DESCRIPTION

The fclose function dissociates the named stream from its underlying file or set of functions. If the stream was being used for output, any buffered data is written first, using fflush(3).

RETURN VALUES

Upon successful completion, 0 is returned. Otherwise, EOF is returned, and the global variable errno is set to indicate the error. In either case, no further access to the stream is possible.

ERRORS

EBADF     The argument stream is not an open stream.

The fclose function may also fail and set errno for any of the errors specified for the routines close(2) or fflush(3).

SEE ALSO

close(2), fflush(3), fopen(3), setbuf(3)

STANDARDS

The fclose function conforms to ANSI C3.159-1989 ("ANSI C").

BSD Man Page, 29 November 1993

clearerr, feof, ferror, fileno

clearerr, feof, ferror, fileno—Check and reset stream status

SYNOPSIS

#include <stdio.h>
void clearerr( FILE *stream);
int feof(FILE *stream);
int ferror(FILE *stream);
int fileno(FILE *stream);

DESCRIPTION

The function clearerr clears the end-of-file and error indicators for the stream pointed to by stream.

The function feof tests the end-of-file indicator for the stream pointed to by stream, returning nonzero if it is set. The end-of-file indicator can only be cleared by the function clearerr.

The function ferror tests the error indicator for the stream pointed to by stream, returning nonzero if it is set. The error indicator can only be reset by the clearerr function.

The function fileno examines the argument stream and returns its integer descriptor.

ERRORS

These functions should not fail and do not set the external variable errno.

SEE ALSO

open(2), stdio(3)

STANDARDS

The functions clearerr, feof, and ferror conform to C3.159-1989 ("ANSI C").

BSD Man Page, 29 November 1993

fflush, fpurge

fflush, fpurge—Flush a stream

SYNOPSIS

#include <stdio.h>
int fflush( FILE *stream);
int fpurge( FILE *stream);

DESCRIPTION

The function fflush forces a write of all buffered data for the given output or update stream via the stream's underlying write function. The open status of the stream is unaffected.

If the stream argument is NULL, fflush flushes all open output streams. (Does this happen under Linux?)

The function fpurge erases any input or output buffered in the given stream. For output streams, this discards any unwritten output. For input streams, this discards any input read from the underlying object but not yet obtained via getc(3); this includes any text pushed back via ungetc.

RETURN VALUES

Upon successful completion, 0 is returned. Otherwise, EOF is returned, and the global variable errno is set to indicate the error.

ERRORS

EBADF     Stream is not an open stream, or, in the case of
fflush, not a stream open for writing.

The function fflush may also fail and set errno for any of the errors specified for the routine write(2).