425 lines
9.9 KiB
HTML
425 lines
9.9 KiB
HTML
|
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
|
|
<HTML><HEAD><TITLE>Man page of STRTOL</TITLE>
|
|
</HEAD><BODY>
|
|
<H1>STRTOL</H1>
|
|
Section: Linux Programmer's Manual (3)<BR>Updated: 2019-10-10<BR><A HREF="#index">Index</A>
|
|
<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
|
|
|
|
<A NAME="lbAB"> </A>
|
|
<H2>NAME</H2>
|
|
|
|
strtol, strtoll, strtoq - convert a string to a long integer
|
|
<A NAME="lbAC"> </A>
|
|
<H2>SYNOPSIS</H2>
|
|
|
|
<PRE>
|
|
<B>#include <<A HREF="file:///usr/include/stdlib.h">stdlib.h</A>></B>
|
|
|
|
<B>long int strtol(const char *</B><I>nptr</I><B>, char **</B><I>endptr</I><B>, int </B><I>base</I><B>);</B>
|
|
|
|
<B>long long int strtoll(const char *</B><I>nptr</I><B>, char **</B><I>endptr</I><B>, int </B><I>base</I><B>);</B>
|
|
</PRE>
|
|
|
|
<P>
|
|
|
|
|
|
Feature Test Macro Requirements for glibc (see
|
|
<B><A HREF="/cgi-bin/man/man2html?7+feature_test_macros">feature_test_macros</A></B>(7)):
|
|
|
|
|
|
<P>
|
|
|
|
|
|
<B>strtoll</B>():
|
|
|
|
<DL COMPACT><DT id="1"><DD>
|
|
_ISOC99_SOURCE
|
|
<BR> || /* Glibc versions <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
|
|
</DL>
|
|
|
|
|
|
<A NAME="lbAD"> </A>
|
|
<H2>DESCRIPTION</H2>
|
|
|
|
The
|
|
<B>strtol</B>()
|
|
|
|
function converts the initial part of the string
|
|
in
|
|
<I>nptr</I>
|
|
|
|
to a long integer value according to the given
|
|
<I>base</I>,
|
|
|
|
which must be between 2 and 36 inclusive, or be the special value 0.
|
|
<P>
|
|
|
|
The string may begin with an arbitrary amount of white space (as
|
|
determined by
|
|
<B><A HREF="/cgi-bin/man/man2html?3+isspace">isspace</A></B>(3))
|
|
|
|
followed by a single optional '+' or '-' sign.
|
|
If
|
|
<I>base</I>
|
|
|
|
is zero or 16, the string may then include a
|
|
"0x" or "0X" prefix, and the number will be read in base 16; otherwise, a
|
|
zero
|
|
<I>base</I>
|
|
|
|
is taken as 10 (decimal) unless the next character
|
|
is '0', in which case it is taken as 8 (octal).
|
|
<P>
|
|
|
|
The remainder of the string is converted to a
|
|
<I>long int</I>
|
|
|
|
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 'A' in
|
|
either uppercase or lowercase represents 10, 'B' represents 11, and so
|
|
forth, with 'Z' representing 35.)
|
|
<P>
|
|
|
|
If
|
|
<I>endptr</I>
|
|
|
|
is not NULL,
|
|
<B>strtol</B>()
|
|
|
|
stores the address of the
|
|
first invalid character in
|
|
<I>*endptr</I>.
|
|
|
|
If there were no digits at
|
|
all,
|
|
<B>strtol</B>()
|
|
|
|
stores the original value of
|
|
<I>nptr</I>
|
|
|
|
in
|
|
<I>*endptr</I>
|
|
|
|
(and returns 0).
|
|
In particular, if
|
|
<I>*nptr</I>
|
|
|
|
is not '\0' but
|
|
<I>**endptr</I>
|
|
|
|
is '\0' on return, the entire string is valid.
|
|
<P>
|
|
|
|
The
|
|
<B>strtoll</B>()
|
|
|
|
function works just like the
|
|
<B>strtol</B>()
|
|
|
|
function but returns a long long integer value.
|
|
<A NAME="lbAE"> </A>
|
|
<H2>RETURN VALUE</H2>
|
|
|
|
The
|
|
<B>strtol</B>()
|
|
|
|
function returns the result of the conversion,
|
|
unless the value would underflow or overflow.
|
|
If an underflow occurs,
|
|
<B>strtol</B>()
|
|
|
|
returns
|
|
<B>LONG_MIN</B>.
|
|
|
|
If an overflow occurs,
|
|
<B>strtol</B>()
|
|
|
|
returns
|
|
<B>LONG_MAX</B>.
|
|
|
|
In both cases,
|
|
<I>errno</I>
|
|
|
|
is set to
|
|
<B>ERANGE</B>.
|
|
|
|
Precisely the same holds for
|
|
<B>strtoll</B>()
|
|
|
|
(with
|
|
<B>LLONG_MIN</B>
|
|
|
|
and
|
|
<B>LLONG_MAX</B>
|
|
|
|
instead of
|
|
<B>LONG_MIN</B>
|
|
|
|
and
|
|
<B>LONG_MAX</B>).
|
|
|
|
<A NAME="lbAF"> </A>
|
|
<H2>ERRORS</H2>
|
|
|
|
<DL COMPACT>
|
|
<DT id="2"><B>EINVAL</B>
|
|
|
|
<DD>
|
|
(not in C99)
|
|
The given
|
|
<I>base</I>
|
|
|
|
contains an unsupported value.
|
|
<DT id="3"><B>ERANGE</B>
|
|
|
|
<DD>
|
|
The resulting value was out of range.
|
|
</DL>
|
|
<P>
|
|
|
|
The implementation may also set
|
|
<I>errno</I>
|
|
|
|
to
|
|
<B>EINVAL</B>
|
|
|
|
in case
|
|
no conversion was performed (no digits seen, and 0 returned).
|
|
<A NAME="lbAG"> </A>
|
|
<H2>ATTRIBUTES</H2>
|
|
|
|
For an explanation of the terms used in this section, see
|
|
<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
|
|
|
|
<TABLE BORDER>
|
|
<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
|
|
<TR VALIGN=top><TD>
|
|
<B>strtol</B>(),
|
|
|
|
<B>strtoll</B>(),
|
|
|
|
<B>strtoq</B>()
|
|
|
|
</TD><TD>Thread safety</TD><TD>MT-Safe locale<BR></TD></TR>
|
|
</TABLE>
|
|
|
|
<A NAME="lbAH"> </A>
|
|
<H2>CONFORMING TO</H2>
|
|
|
|
<B>strtol</B>():
|
|
|
|
POSIX.1-2001, POSIX.1-2008, C89, C99 SVr4, 4.3BSD.
|
|
<P>
|
|
|
|
<B>strtoll</B>():
|
|
|
|
POSIX.1-2001, POSIX.1-2008, C99.
|
|
<A NAME="lbAI"> </A>
|
|
<H2>NOTES</H2>
|
|
|
|
Since
|
|
<B>strtol</B>()
|
|
|
|
can legitimately return 0,
|
|
<B>LONG_MAX</B>,
|
|
|
|
or
|
|
<B>LONG_MIN</B>
|
|
|
|
(<B>LLONG_MAX</B>
|
|
|
|
or
|
|
<B>LLONG_MIN</B>
|
|
|
|
for
|
|
<B>strtoll</B>())
|
|
|
|
on both success and failure, the calling program should set
|
|
<I>errno</I>
|
|
|
|
to 0 before the call,
|
|
and then determine if an error occurred by checking whether
|
|
<I>errno</I>
|
|
|
|
has a nonzero value after the call.
|
|
<P>
|
|
|
|
According to POSIX.1,
|
|
in locales other than the "C" and "POSIX",
|
|
these functions may accept other,
|
|
implementation-defined numeric strings.
|
|
<P>
|
|
|
|
BSD also has
|
|
<P>
|
|
|
|
|
|
|
|
<B>quad_t strtoq(const char *</B><I>nptr</I><B>, char **</B><I>endptr</I><B>, int </B><I>base</I><B>);</B>
|
|
|
|
|
|
|
|
<P>
|
|
|
|
with completely analogous definition.
|
|
Depending on the wordsize of the current architecture, this
|
|
may be equivalent to
|
|
<B>strtoll</B>()
|
|
|
|
or to
|
|
<B>strtol</B>().
|
|
|
|
<A NAME="lbAJ"> </A>
|
|
<H2>EXAMPLE</H2>
|
|
|
|
The program shown below demonstrates the use of
|
|
<B>strtol</B>().
|
|
|
|
The first command-line argument specifies a string from which
|
|
<B>strtol</B>()
|
|
|
|
should parse a number.
|
|
The second (optional) argument specifies the base to be used for
|
|
the conversion.
|
|
(This argument is converted to numeric form using
|
|
<B><A HREF="/cgi-bin/man/man2html?3+atoi">atoi</A></B>(3),
|
|
|
|
a function that performs no error checking and
|
|
has a simpler interface than
|
|
<B>strtol</B>().)
|
|
|
|
Some examples of the results produced by this program are the following:
|
|
<P>
|
|
|
|
|
|
|
|
$<B> ./a.out 123</B>
|
|
|
|
strtol() returned 123
|
|
$<B> ./a.out ' 123'</B>
|
|
|
|
strtol() returned 123
|
|
$<B> ./a.out 123abc</B>
|
|
|
|
strtol() returned 123
|
|
Further characters after number: abc
|
|
$<B> ./a.out 123abc 55</B>
|
|
|
|
strtol: Invalid argument
|
|
$<B> ./a.out ''</B>
|
|
|
|
No digits were found
|
|
$<B> ./a.out 4000000000</B>
|
|
|
|
strtol: Numerical result out of range
|
|
|
|
|
|
<A NAME="lbAK"> </A>
|
|
<H3>Program source</H3>
|
|
|
|
|
|
|
|
#include <<A HREF="file:///usr/include/stdlib.h">stdlib.h</A>>
|
|
#include <<A HREF="file:///usr/include/limits.h">limits.h</A>>
|
|
#include <<A HREF="file:///usr/include/stdio.h">stdio.h</A>>
|
|
#include <<A HREF="file:///usr/include/errno.h">errno.h</A>>
|
|
<P>
|
|
int
|
|
main(int argc, char *argv[])
|
|
{
|
|
<BR> int base;
|
|
<BR> char *endptr, *str;
|
|
<BR> long val;
|
|
<P>
|
|
<BR> if (argc < 2) {
|
|
<BR> fprintf(stderr, "Usage: %s str [base]\n", argv[0]);
|
|
<BR> exit(EXIT_FAILURE);
|
|
<BR> }
|
|
<P>
|
|
<BR> str = argv[1];
|
|
<BR> base = (argc > 2) ? atoi(argv[2]) : 10;
|
|
<P>
|
|
<BR> errno = 0; /* To distinguish success/failure after call */
|
|
<BR> val = strtol(str, &endptr, base);
|
|
<P>
|
|
<BR> /* Check for various possible errors */
|
|
<P>
|
|
<BR> if ((errno == ERANGE && (val == LONG_MAX || val == LONG_MIN))
|
|
<BR> || (errno != 0 && val == 0)) {
|
|
<BR> perror("strtol");
|
|
<BR> exit(EXIT_FAILURE);
|
|
<BR> }
|
|
<P>
|
|
<BR> if (endptr == str) {
|
|
<BR> fprintf(stderr, "No digits were found\n");
|
|
<BR> exit(EXIT_FAILURE);
|
|
<BR> }
|
|
<P>
|
|
<BR> /* If we got here, strtol() successfully parsed a number */
|
|
<P>
|
|
<BR> printf("strtol() returned %ld\n", val);
|
|
<P>
|
|
<BR> if (*endptr != '\0') /* Not necessarily an error... */
|
|
<BR> printf("Further characters after number: %s\n", endptr);
|
|
<P>
|
|
<BR> exit(EXIT_SUCCESS);
|
|
}
|
|
|
|
<A NAME="lbAL"> </A>
|
|
<H2>SEE ALSO</H2>
|
|
|
|
<B><A HREF="/cgi-bin/man/man2html?3+atof">atof</A></B>(3),
|
|
|
|
<B><A HREF="/cgi-bin/man/man2html?3+atoi">atoi</A></B>(3),
|
|
|
|
<B><A HREF="/cgi-bin/man/man2html?3+atol">atol</A></B>(3),
|
|
|
|
<B><A HREF="/cgi-bin/man/man2html?3+strtod">strtod</A></B>(3),
|
|
|
|
<B><A HREF="/cgi-bin/man/man2html?3+strtoimax">strtoimax</A></B>(3)
|
|
|
|
<B><A HREF="/cgi-bin/man/man2html?3+strtoul">strtoul</A></B>(3),
|
|
|
|
<A NAME="lbAM"> </A>
|
|
<H2>COLOPHON</H2>
|
|
|
|
This page is part of release 5.05 of the Linux
|
|
<I>man-pages</I>
|
|
|
|
project.
|
|
A description of the project,
|
|
information about reporting bugs,
|
|
and the latest version of this page,
|
|
can be found at
|
|
<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
|
|
<P>
|
|
|
|
<HR>
|
|
<A NAME="index"> </A><H2>Index</H2>
|
|
<DL>
|
|
<DT id="4"><A HREF="#lbAB">NAME</A><DD>
|
|
<DT id="5"><A HREF="#lbAC">SYNOPSIS</A><DD>
|
|
<DT id="6"><A HREF="#lbAD">DESCRIPTION</A><DD>
|
|
<DT id="7"><A HREF="#lbAE">RETURN VALUE</A><DD>
|
|
<DT id="8"><A HREF="#lbAF">ERRORS</A><DD>
|
|
<DT id="9"><A HREF="#lbAG">ATTRIBUTES</A><DD>
|
|
<DT id="10"><A HREF="#lbAH">CONFORMING TO</A><DD>
|
|
<DT id="11"><A HREF="#lbAI">NOTES</A><DD>
|
|
<DT id="12"><A HREF="#lbAJ">EXAMPLE</A><DD>
|
|
<DL>
|
|
<DT id="13"><A HREF="#lbAK">Program source</A><DD>
|
|
</DL>
|
|
<DT id="14"><A HREF="#lbAL">SEE ALSO</A><DD>
|
|
<DT id="15"><A HREF="#lbAM">COLOPHON</A><DD>
|
|
</DL>
|
|
<HR>
|
|
This document was created by
|
|
<A HREF="/cgi-bin/man/man2html">man2html</A>,
|
|
using the manual pages.<BR>
|
|
Time: 00:05:58 GMT, March 31, 2021
|
|
</BODY>
|
|
</HTML>
|