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.\" Copyright (c) 1990, 1991 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Chris Torek and the American National Standards Committee X3,
.\" on Information Processing Systems.
.\"
.\" 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.
.\" 3. All advertising materials mentioning features or use of this software
.\" must display the following acknowledgement:
.\" This product includes software developed by the University of
.\" California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
.\" 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.
.\"
.\" $OpenBSD: strtol.3,v 1.11 2002/11/21 20:54:09 millert Exp $
.\"
.Dd June 25, 1992
.Dt STRTOL 3
.Os
.Sh NAME
.Nm strtol ,
.Nm strtoll ,
.Nm strtoq
.Nd convert string value to a long or long long integer
.Sh SYNOPSIS
.Fd #include <stdlib.h>
.Fd #include <limits.h>
.Ft long
.Fn strtol "const char *nptr" "char **endptr" "int base"
.Pp
.Fd #include <stdlib.h>
.Fd #include <limits.h>
.Ft long long
.Fn strtoll "const char *nptr" "char **endptr" "int base"
.Pp
.Fd #include <sys/types.h>
.Fd #include <stdlib.h>
.Fd #include <limits.h>
.Ft quad_t
.Fn strtoq "const char *nptr" "char **endptr" "int base"
.Sh DESCRIPTION
The
.Fn strtol
function converts the string in
.Fa nptr
to a
.Li long
value.
The
.Fn strtoll
function converts the string in
.Fa nptr
to a
.Li long long
value.
The
.Fn strtoq
function is a deprecated equivalent of
.Fn strtoll
and is provided for backwards compatibility with legacy programs.
The conversion is done according to the given
.Fa base ,
which must be a number between 2 and 36 inclusive or the special value 0.
.Pp
The string may begin with an arbitrary amount of whitespace
(as determined by
.Xr isspace 3 )
followed by a single optional
.Ql +
or
.Ql -
sign.
If
.Fa base
is zero or 16, the string may then include a
.Ql 0x
prefix, and the number will be read in base 16; otherwise, a zero
.Fa base
is taken as 10 (decimal) unless the next character is
.Ql 0 ,
in which case it is taken as 8 (octal).
.Pp
The remainder of the string is converted to a
.Li long
value in the obvious manner,
stopping at the first character which is not a valid digit
in the given base.
(In bases above 10, the letter
.Ql A
in either upper or lower case represents 10,
.Ql B
represents 11, and so forth, with
.Ql Z
representing 35.)
.Pp
If
.Fa endptr
is non-null,
.Fn strtol
stores the address of the first invalid character in
.Fa *endptr .
If there were no digits at all, however,
.Fn strtol
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 strtol
function returns the result of the conversion,
unless the value would underflow or overflow.
If an underflow occurs,
.Fn strtol
returns
.Dv LONG_MIN .
If an overflow occurs,
.Fn strtol
returns
.Dv LONG_MAX .
In both cases,
.Va errno
is set to
.Er ERANGE .
.Pp
The
.Fn strtoll
function has identical return values except that
.Dv LLONG_MIN
and
.Dv LLONG_MAX
are used to indicate underflow and overflow respectively.
.Sh EXAMPLES
Ensuring that a string is a valid number (i.e., in range and containing no
trailing characters) requires clearing
.Va errno
beforehand explicitly since
.Va errno
is not changed on a successful call to
.Fn strtol ,
and the return value of
.Fn strtol
cannot be used unambiguously to signal an error:
.Bd -literal -offset indent
char *ep;
long lval;
\&...
errno = 0;
lval = strtol(buf, &ep, 10);
if (buf[0] == '\e0' || *ep != '\e0')
goto not_a_number;
if (errno == ERANGE && (lval == LONG_MAX || lval == LONG_MIN))
goto out_of_range;
.Ed
.Pp
This example will accept
.Dq 12
but not
.Dq 12foo
or
.Dq 12\en .
If trailing whitespace is acceptable, further checks must be done on
.Va *ep ;
alternately, use
.Xr sscanf 3 .
.Pp
If
.Fn strtol
is being used instead of
.Xr atoi 3 ,
error checking is further complicated because the desired return value is an
.Li int
rather than a
.Li long ;
however, on some architectures integers and long integers are the same size.
Thus the following is necessary:
.Bd -literal -offset indent
char *ep;
int ival;
long lval;
\&...
errno = 0;
lval = strtol(buf, &ep, 10);
if (buf[0] == '\e0' || *ep != '\e0')
goto not_a_number;
if ((errno == ERANGE && (lval == LONG_MAX || lval == LONG_MIN)) ||
(lval > INT_MAX || lval < INT_MIN))
goto out_of_range;
ival = lval;
.Ed
.Sh ERRORS
.Bl -tag -width Er
.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 atoll 3 ,
.Xr sscanf 3 ,
.Xr strtod 3 ,
.Xr strtoul 3
.Sh STANDARDS
The
.Fn strtol
and
.Fn strtoll
functions conform to
.St -ansiC-99 .
The
.Fn strtoq
function is a
.Bx
extension and is provided for backwards compatibility with legacy programs.
.Sh BUGS
Ignores the current locale.
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