freebsd-dev/lib/libc/stdlib/strtoul.3

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.\" Copyright (c) 1990, 1991, 1993
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.\" This code is derived from software contributed to Berkeley by
.\" Chris Torek and the American National Standards Committee X3,
.\" on Information Processing Systems.
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.\" may be used to endorse or promote products derived from this software
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.\" @(#)strtoul.3 8.1 (Berkeley) 6/4/93
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.\" $FreeBSD$
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.\"
.Dd November 28, 2001
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.Dt STRTOUL 3
.Os
.Sh NAME
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.Nm strtoul , strtoull , strtoumax , strtouq
.Nd "convert a string to an"
.Vt "unsigned long" , "unsigned long long" , uintmax_t ,
or
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.Vt u_quad_t
integer
.Sh LIBRARY
.Lb libc
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.Sh SYNOPSIS
.In stdlib.h
.In limits.h
.Ft "unsigned long"
.Fn strtoul "const char * restrict nptr" "char ** restrict endptr" "int base"
.Ft "unsigned long long"
.Fn strtoull "const char * restrict nptr" "char ** restrict endptr" "int base"
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.In inttypes.h
.Ft uintmax_t
.Fn strtoumax "const char * restrict nptr" "char ** restrict endptr" "int base"
.In sys/types.h
.In stdlib.h
.In limits.h
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.Ft u_quad_t
.Fn strtouq "const char *nptr" "char **endptr" "int base"
.Sh DESCRIPTION
The
.Fn strtoul
function
converts the string in
.Fa nptr
to an
.Vt "unsigned long"
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value.
The
.Fn strtoull
function
converts the string in
.Fa nptr
to an
.Vt "unsigned long long"
value.
The
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.Fn strtoumax
function
converts the string in
.Fa nptr
to an
.Vt uintmax_t
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value.
The
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.Fn strtouq
function
converts the string in
.Fa nptr
to a
.Vt u_quad_t
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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
.Dq Li 0x
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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 an
.Vt "unsigned long"
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value in the obvious manner,
stopping at the end of the string
or at the first character that does not produce 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 not
.Dv NULL ,
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.Fn strtoul
stores the address of the first invalid character in
.Fa *endptr .
If there were no digits at all, however,
.Fn strtoul
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
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.Fn strtoul ,
.Fn strtoull ,
.Fn strtoumax
and
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.Fn strtouq
functions
return either the result of the conversion
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or, if there was a leading minus sign,
the negation of the result of the conversion,
unless the original (non-negated) value would overflow;
in the latter case,
.Fn strtoul
returns
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.Dv ULONG_MAX ,
.Fn strtoull
returns
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.Dv ULLONG_MAX ,
.Fn strtoumax
returns
.Dv UINTMAX_MAX ,
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and
.Fn strtouq
returns
.Dv ULLONG_MAX .
In all cases,
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.Va errno
is set to
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.Er ERANGE .
If no conversion could be performed, 0 is returned and
the global variable
.Va errno
is set to
.Er EINVAL
(the last feature is not portable across all platforms).
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.Sh ERRORS
.Bl -tag -width Er
.It Bq Er EINVAL
The value of
.Fa base
is not supported or
no conversion could be performed
(the last feature is not portable across all platforms).
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.It Bq Er ERANGE
The given string was out of range; the value converted has been clamped.
.El
.Sh SEE ALSO
.Xr strtol 3 ,
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.Xr strtonum 3 ,
.Xr wcstoul 3
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.Sh STANDARDS
The
.Fn strtoul
function
conforms to
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.St -isoC .
The
.Fn strtoull
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and
.Fn strtoumax
functions
conform to
.St -isoC-99 .
The
.Bx
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.Fn strtouq
function is deprecated.