Date: Sat, 8 Feb 2003 14:59:21 +0100 From: Eirik Nygaard <eirikn@bluezone.no> To: standards@FreeBSD.ORG Subject: strtof() Message-ID: <20030208135921.GA72899@eirikn.net>
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I tave made a strtof(3) function.
Attached is the function, a small test program and the man page.
I will also start on the strtold(3) now.
--=20
Eirik Nygaard <eirikn@bluezone.no>
PGP Key: 83C55EDE
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/*
*
* Copyright (c) 2003 Eirik Nygaard <eirikn@bluezone.no>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPO=
SE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTI=
AL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRI=
CT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <float.h>
#include <errno.h>
#include <stdlib.h>
float
strtof(const char * __restrict nptr, char ** __restrict endptr)
{
char c;
const char *s;
float acc, decnum;
int neg, any, dec, deccnt, a;
=09
s =3D nptr;
do {
c =3D *s++;
} while (isspace((unsigned char)c));
if (c =3D=3D '-') {
neg =3D 1;
c =3D *s++;
} else {
neg =3D 0;
if (c =3D=3D '+')
c =3D *s++;
}
=09
any =3D acc =3D dec =3D 0;
for ( ; ; c =3D *s++) {
if (c =3D=3D '.') {
dec =3D 1;
deccnt =3D 0;
continue;
}
if (c >=3D '0' && c <=3D '9')
c -=3D '0';
else
break;
any =3D 1;
if (dec) {
deccnt++;
a =3D deccnt;
decnum =3D c;
for (; a > 0; a--)
decnum /=3D 10;
if ((FLT_MAX - decnum < acc) && !neg) {
any =3D -1;
break;
}
if ((FLT_MIN + decnum < acc) && neg) {
any =3D -1;
break;
}
else {
if (neg)
acc -=3D decnum;
else
acc +=3D decnum;
}
}
else {
any =3D 1;
acc *=3D 10;
if ((FLT_MAX - c < acc) && !neg) {
any =3D -1;
break;
}
if ((FLT_MIN + c < acc) && neg) {
any =3D -1;
break;
}
else {
if (neg)
acc -=3D c;
else
acc +=3D c;
}
}
}
if (any < 0) {
acc =3D neg ? FLT_MIN : FLT_MAX;
errno =3D ERANGE;
} else if (!any)
errno =3D EINVAL;
=09
if (endptr !=3D NULL)
*endptr =3D (char *)(any ? s - 1 : nptr);
return (acc);
}
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.\" Copyright (c) 2003 Eirik Nygaard <eirikn@bluezone.no>
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd February 8, 2003
.Dt STRTOF 3
.Os
.Sh NAME
.Nm strtof
.Nd "convert a string value to a"
.Vt float
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdlib.h
.Ft float
.Fn strtof "const char * restrict nptr" "char ** restrict endptr"
.Sh DESCRIPTION
The
.Fn strtof
function
converts the string in
.Fa nptr
to a
.Vt float
value.
.Pp
The string may begin with an arbitrary amount of white space
(as determined by
.Xr isspace 3 )
followed by a single optional
.Ql +
or
.Ql -
sign.
.Pp
The remainder of the string is converted to a
.Vt float
value in the obvious manner,
stopping at the first character which is not a valid digit.
.Pp
If
.Fa endptr
is not
.Dv NULL ,
.Fn strtof
stores the address of the first invalid character in
.Fa *endptr .
If there were no digits at all, however,
.Fn strtof
stores the original value of
.Fa nptr
in
.Fa *endptr .
(Thus, if
.Fa *nptr
is not
.Ql \e0
but
.Fa **endptr
is
.Ql \e0
on return, the entire string was valid.)
.Sh RETURN VALUES
The
.Fn strtof ,
function
return the result of the conversion,
unless the value would underflow or overflow.
If no conversion could be performed, 0 is returned and
the global variable
.Va errno
is set to
.Er EINVAL .
If an overflow or underflow occurs,
.Va errno
is set to
.Er ERANGE
and the function return value is clamped according
to the following table.
.Bl -column -offset indent ".Fn strtoimax" ".Sy overflow" ".Sy underflow"
.It Sy Function Ta Sy overflow Ta Sy underflow
.It Fn strtof Ta Dv FLT_MIN Ta Dv FLT_MAX
.El
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er EINVAL
The value of
.Fa base
is not supported or
no conversion could be performed.
.It Bq Er ERANGE
The given string was out of range; the value converted has been clamped.
.El
.Sh SEE ALSO
.Xr atof 3 ,
.Xr atoi 3 ,
.Xr atol 3 ,
.Xr strtod 3 ,
.Xr strtoul 3 ,
.Xr strtol 3 ,
.Xr wcstol 3
.Sh STANDARDS
The
.Fn strtof
function
conform to
.St -isoC-99 .
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#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
int
main ()
{
char *endp;
float f;
f = strtof("-5214.452", &endp);
if (errno == ERANGE)
printf("ERANGE\n");
else if (errno == EINVAL)
printf("EINVAL\n");
else
printf("It's a float with value %f\n", f);
return 0;
}
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