path: root/usr/src/man/man3c/strtol.3c

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.TH STRTOL 3C "May 6, 2003"
.SH NAME
strtol, strtoll, atol, atoll, atoi, lltostr, ulltostr \- string conversion
routines
.SH SYNOPSIS
.LP
.nf
#include <stdlib.h>

\fBlong\fR \fBstrtol\fR(\fBconst char *restrict\fR \fIstr\fR, \fBchar **restrict\fR \fIendptr\fR, \fBint\fR \fIbase\fR);
.fi

.LP
.nf
\fBlong long\fR \fBstrtoll\fR(\fBconst char *restrict\fR \fIstr\fR, \fBchar **restrict\fR \fIendptr\fR,
     \fBint\fR \fIbase\fR);
.fi

.LP
.nf
\fBlong\fR \fBatol\fR(\fBconst char *\fR\fIstr\fR);
.fi

.LP
.nf
\fBlong long\fR \fBatoll\fR(\fBconst char *\fR\fIstr\fR);
.fi

.LP
.nf
\fBint\fR \fBatoi\fR(\fBconst char *\fR\fIstr\fR);
.fi

.LP
.nf
\fBchar *\fR\fBlltostr\fR(\fBlong long\fR \fIvalue\fR, \fBchar *\fR\fIendptr\fR);
.fi

.LP
.nf
\fBchar *\fR\fBulltostr\fR(\fBunsigned long long\fR \fIvalue\fR, \fBchar *\fR\fIendptr\fR);
.fi

.SH DESCRIPTION
.SS "\fBstrtol()\fR and \fBstrtoll()\fR"
.sp
.LP
The \fBstrtol()\fR function converts the initial portion of the string pointed
to by \fIstr\fR to a type \fBlong int\fR representation.
.sp
.LP
The \fBstrtoll()\fR function converts the initial portion of the string pointed
to by \fIstr\fR to a type \fBlong long\fR representation.
.sp
.LP
Both functions first decompose the input string into three parts: an initial,
possibly empty, sequence of white-space characters (as specified by
\fBisspace\fR(3C)); a subject sequence interpreted as an integer represented in
some radix determined by the value of \fIbase\fR; and a final string of one or
more unrecognized characters, including the terminating null byte of the input
string. They then attempt to convert the subject sequence to an integer and
return the result.
.sp
.LP
If the value of \fIbase\fR is 0, the expected form of the subject sequence is
that of a decimal constant, octal constant or hexadecimal constant, any of
which may be preceded by a + or \(mi sign. A decimal constant begins with a
non-zero digit, and consists of a sequence of decimal digits. An octal constant
consists of the prefix 0 optionally followed by a sequence of the digits 0 to 7
only. A hexadecimal constant consists of the prefix 0x or 0X followed by a
sequence of the decimal digits and letters a (or A) to f (or F) with values 10
to 15 respectively.
.sp
.LP
If the value of \fIbase\fR is between 2 and 36, the expected form of the
subject sequence is a sequence of letters and digits representing an integer
with the radix specified by \fIbase\fR, optionally preceded by a + or \(mi
sign. The letters from a (or A) to z (or Z) inclusive are ascribed the values
10 to 35; only letters whose ascribed values are less than that of \fIbase\fR
are permitted. If the value of \fIbase\fR is 16, the characters 0x or 0X may
optionally precede the sequence of letters and digits, following the sign if
present.
.sp
.LP
The subject sequence is defined as the longest initial subsequence of the input
string, starting with the first non-white-space character, that is of the
expected form. The subject sequence contains no characters if the input string
is empty or consists entirely of white-space characters, or if the first
non-white-space character is other than a sign or a permissible letter or
digit.
.sp
.LP
If the subject sequence has the expected form and the value of \fIbase\fR is 0,
the sequence of characters starting with the first digit is interpreted as an
integer constant. If the subject sequence has the expected form and the value
of \fIbase\fR is between 2 and 36, it is used as the base for conversion,
ascribing to each letter its value as given above. If the subject sequence
begins with a minus sign, the value resulting from the conversion is negated. A
pointer to the final string is stored in the object pointed to by \fIendptr\fR,
provided that \fIendptr\fR is not a null pointer.
.sp
.LP
In other than the POSIX locale, additional implementation-dependent subject
sequence forms may be accepted.
.sp
.LP
If the subject sequence is empty or does not have the expected form, no
conversion is performed; the value of \fIstr\fR is stored in the object pointed
to by \fIendptr\fR, provided that \fIendptr\fR is not a null pointer.
.SS "\fBatol()\fR, \fBatoll()\fR and \fBatoi()\fR"
.sp
.LP
Except for behavior on error, \fBatol()\fR is equivalent to: \fBstrtol(str,
(char **)NULL, 10)\fR.
.sp
.LP
Except for behavior on error, \fBatoll()\fR is equivalent to: \fBstrtoll(str,
(char **)NULL, 10)\fR.
.sp
.LP
Except for behavior on error, \fBatoi()\fR is equivalent to: \fB(int)
strtol(str, (char **)NULL, 10)\fR.
.sp
.LP
If the value cannot be represented, the behavior is undefined.
.SS "\fBlltostr()\fR and \fBulltostr()\fR"
.sp
.LP
The \fBlltostr()\fR function returns a pointer to the string represented by the
\fBlong\fR \fBlong\fR \fIvalue\fR. The \fIendptr\fR argument is assumed to
point to the byte following a storage area into which the decimal
representation of \fIvalue\fR is to be placed as a string.  The \fBlltostr()\fR
function converts \fIvalue\fR to decimal and produces the string,  and returns
a pointer to the beginning of the string. No leading zeros are produced, and no
terminating null is produced. The low-order digit of the result always occupies
memory position  \fIendptr\fR\(mi1. The behavior of \fBlltostr()\fR is
undefined if  \fIvalue\fR is negative.  A single zero digit is produced if
\fIvalue\fR is 0.
.sp
.LP
The \fBulltostr()\fR function is similar to \fBlltostr()\fR except that
\fIvalue\fR is an \fBunsigned long long\fR.
.SH RETURN VALUES
.sp
.LP
Upon successful completion, \fBstrtol()\fR, \fBstrtoll()\fR, \fBatol()\fR,
\fBatoll()\fR, and \fBatoi()\fR return the converted value, if any. If no
conversion could be performed, \fBstrtol()\fR and \fBstrtoll()\fR return
\fB0\fR and \fBerrno\fR may be set to \fBEINVAL\fR.
.sp
.LP
If the correct value is outside the range of representable values,
\fBstrtol()\fR returns \fBLONG_MAX\fR or \fBLONG_MIN\fR and \fBstrtoll()\fR
returns \fBLLONG_MAX\fR or \fBLLONG_MIN\fR (according to the sign of the
value), and \fBerrno\fR is set to \fBERANGE\fR.
.sp
.LP
Upon successful completion, \fBlltostr()\fR and \fBulltostr()\fR return a
pointer to the converted string.
.SH ERRORS
.sp
.LP
The \fBstrtol()\fR and \fBstrtoll()\fR functions will fail if:
.sp
.ne 2
.na
\fB\fBERANGE\fR\fR
.ad
.RS 10n
The value to be returned is not representable. The \fBstrtol()\fR and
\fBstrtoll()\fR functions may fail if:
.RE

.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
The value of \fIbase\fR is not supported.
.RE

.SH USAGE
.sp
.LP
Because 0, \fBLONG_MIN\fR, \fBLONG_MAX\fR, \fBLLONG_MIN\fR, and \fBLLONG_MAX\fR
are returned on error and are also valid returns on success, an application
wishing to check for error situations should set \fBerrno\fR to 0, call the
function, then check \fBerrno\fR and if it is non-zero, assume an error has
occurred.
.sp
.LP
The \fBstrtol()\fR function no longer accepts values greater than
\fBLONG_MAX\fR or \fBLLONG_MAX\fR as valid input. Use \fBstrtoul\fR(3C)
instead.
.sp
.LP
Calls to \fBatoi()\fR and \fBatol()\fR might be faster than corresponding calls
to \fBstrtol()\fR, and calls to \fBatoll()\fR might be faster than
corresponding calls to \fBstrtoll()\fR. However, applications should not use
the \fBatoi()\fR, \fBatol()\fR, or \fBatoll()\fR functions unless they know the
value represented by the argument will be in range for the corresponding result
type.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	See below.
_
MT-Level	MT-Safe
.TE

.sp
.LP
The \fBstrtol()\fR, \fBstrtoll()\fR, \fBatol()\fR, \fBatoll()\fR, and
\fBatoi()\fR functions are Standard.
.SH SEE ALSO
.sp
.LP
\fBisalpha\fR(3C), \fBisspace\fR(3C), \fBscanf\fR(3C), \fBstrtod\fR(3C),
\fBstrtoul\fR(3C), \fBattributes\fR(5), \fBstandards\fR(5)