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strtof (3)

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strtof (3) ( Русские man: Библиотечные вызовы )

strtof (3) ( Linux man: Библиотечные вызовы )

strtof (3) ( POSIX man: Библиотечные вызовы )

BSD mandoc

NAME



strtod , strtof , strtold

 - convert

ASCII

string to floating point

LIBRARY

Lb libc

SYNOPSIS

#include <stdlib.h>
double strtod (const char * restrict nptr char ** restrict endptr);
float strtof (const char * restrict nptr char ** restrict endptr);
long double strtold (const char * restrict nptr char ** restrict endptr);

DESCRIPTION

These conversion functions convert the initial portion of the string pointed to by Fa nptr to Vt double , Vt float , and Vt long double representation, respectively.

The expected form of the string is an optional plus (``+'') or minus sign (``-'') followed by either:

a decimal significand consisting of a sequence of decimal digits optionally containing a decimal-point character, or
a hexadecimal significand consisting of a ``0X'' or ``0x'' followed by a sequence of hexadecimal digits optionally containing a decimal-point character.

In both cases, the significand may be optionally followed by an exponent. An exponent consists of an ``E'' or ``e'' (for decimal constants) or a ``P'' or ``p'' (for hexadecimal constants), followed by an optional plus or minus sign, followed by a sequence of decimal digits. For decimal constants, the exponent indicates the power of 10 by which the significand should be scaled. For hexadecimal constants, the scaling is instead done by powers of 2.

Alternatively, if the portion of the string following the optional plus or minus sign begins with ``INFINITY'' or ``NAN'', ignoring case, it is interpreted as an infinity or a quiet NaN, respectively.

In any of the above cases, leading white-space characters in the string (as defined by the isspace(3) function) are skipped. The decimal point character is defined in the program's locale (category LC_NUMERIC )

RETURN VALUES

The strtod (,);
strtof (,);
and strtold ();
functions return the converted value, if any.

If Fa endptr is not NULL a pointer to the character after the last character used in the conversion is stored in the location referenced by Fa endptr .

If no conversion is performed, zero is returned and the value of Fa nptr is stored in the location referenced by Fa endptr .

If the correct value would cause overflow, plus or minus HUGE_VAL HUGE_VALF or HUGE_VALL is returned (according to the sign and type of the return value), and Er ERANGE is stored in errno If the correct value would cause underflow, zero is returned and Er ERANGE is stored in errno

ERRORS

Bq Er ERANGE: Overflow or underflow occurred.

STANDARDS

The strtod ();
function conforms to St -isoC-99 , with the exception of the bug noted below.

AUTHORS

The author of this software is An David M. Gay .

Copyright (c) 1998 by Lucent Technologies
All Rights Reserved

Permission to use, copy, modify, and distribute this software and
its documentation for any purpose and without fee is hereby
granted, provided that the above copyright notice appear in all
copies and that both that the copyright notice and this
permission notice and warranty disclaimer appear in supporting
documentation, and that the name of Lucent or any of its entities
not be used in advertising or publicity pertaining to
distribution of the software without specific, written prior
permission.

LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
THIS SOFTWARE.