xref: /freebsd/lib/libc/stdlib/strtol.3 (revision 25bb73e063c17cd9048cf60100dbc0ac5177e94a)

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.\"     @(#)strtol.3	8.1 (Berkeley) 6/4/93
.\" $FreeBSD$
.\"
.Dd June 4, 1993
.Dt STRTOL 3
.Os
.Sh NAME
.Nm strtol, strtoq
.Nd convert string value to a long or quad_t integer
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.Fd #include <stdlib.h>
.Fd #include <limits.h>
.Ft long
.Fn strtol "const char *nptr" "char **endptr" "int base"

.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
.Em long
value.
The
.Fn strtoq
function
converts the string in
.Fa nptr
to a
.Em quad_t
value.
The conversion is done according to the given
.Fa base ,
which must be between 2 and 36 inclusive,
or be the special value 0.
.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.
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
.Em 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 nil,
.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 .
.Sh ERRORS
.Bl -tag -width [ERANGE]
.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
.Sh STANDARDS
The
.Fn strtol
function
conforms to
.St -ansiC .
.Sh BUGS
Ignores the current locale.