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

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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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.\" @(#)strtol.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 STRTOL 3
.Os
.Sh NAME
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.Nm strtol , strtoll , strtoimax , strtoq
.Nd "convert a string value to a"
.Vt long , "long long" , intmax_t
or
.Vt quad_t
integer
.Sh LIBRARY
.Lb libc
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.Sh SYNOPSIS
.In stdlib.h
.In limits.h
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.Ft long
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.Fn strtol "const char *nptr" "char **endptr" "int base"
.Ft long long
.Fn strtoll "const char *nptr" "char **endptr" "int base"
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.In inttypes.h
.Ft intmax_t
.Fn strtoimax "const char *nptr" "char **endptr" "int base"
.In sys/types.h
.In stdlib.h
.In limits.h
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.Ft quad_t
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.Fn strtoq "const char *nptr" "char **endptr" "int base"
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.Sh DESCRIPTION
The
.Fn strtol
function
converts the string in
.Fa nptr
to a
.Vt long
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value.
The
.Fn strtoll
function
converts the string in
.Fa nptr
to a
.Vt "long long"
value.
The
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.Fn strtoimax
function
converts the string in
.Fa nptr
to an
.Vt intmax_t
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value.
The
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.Fn strtoq
function
converts the string in
.Fa nptr
to a
.Vt 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 a
.Vt long , "long long" , intmax_t
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or
.Vt quad_t
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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 not
.Dv NULL ,
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.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
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.Fn strtol ,
.Fn strtoll ,
.Fn strtoimax
and
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.Fn strtoq
functions
return the result of the conversion,
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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 .
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If an overflow or underflow occurs,
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.Va errno
is set to
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.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 strtol Ta Dv LONG_MIN Ta Dv LONG_MAX
.It Fn strtoll Ta Dv LLONG_MIN Ta Dv LLONG_MAX
.It Fn strtoimax Ta Dv INTMAX_MIN Ta Dv INTMAX_MAX
.It Fn strtoq Ta Dv LLONG_MIN Ta Dv LLONG_MAX
.El
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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.
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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 atof 3 ,
.Xr atoi 3 ,
.Xr atol 3 ,
.Xr strtod 3 ,
.Xr strtoul 3
.Sh STANDARDS
The
.Fn strtol
function
conforms to
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.St -isoC .
The
.Fn strtoll
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and
.Fn strtoimax
functions
conform to
.St -isoC-99 .
The
.Bx
.Fn strtoq
function is deprecated.