Name
atoi, atol, atoll — convert a string to an integer
Synopsis
#include <stdlib.h>
int
atoi( |
const char *nptr); |
long
atol( |
const char *nptr); |
long long
atoll( |
const char *nptr); |
![[Note]](../stylesheet/note.png) |
Note | |||
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DESCRIPTION
The atoi() function converts
the initial portion of the string pointed to by nptr to int. The behavior is the same as
strtol(nptr, NULL, 10);
except that atoi() does not
detect errors.
The atol() and atoll() functions behave the same as
atoi(), except that they
convert the initial portion of the string to their return
type of long or long long.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
| Interface | Attribute | Value |
atoi(), atol(), atoll() |
Thread safety | MT-Safe locale |
CONFORMING TO
POSIX.1-2001, POSIX.1-2008, C99, SVr4, 4.3BSD. C89 and
POSIX.1-1996 include the functions atoi() and atol() only.
NOTES
POSIX.1 leaves the return value of atoi() on error unspecified. On glibc, musl
libc, and uClibc, 0 is returned on error.
BUGS
errno is not set on error so
there is no way to distinguish between 0 as an error and as
the converted value. No checks for overflow or underflow are
done. Only base-10 input can be converted. It is recommended
to instead use the strtol() and
strtoul() family of functions
in new programs.
COLOPHON
This page is part of release 5.11 of the Linux man-pages project. A
description of the project, information about reporting bugs,
and the latest version of this page, can be found at
https://www.kernel.org/doc/man−pages/.
|
Copyright 1993 David Metcalfe (davidprism.demon.co.uk) %%%LICENSE_START(VERBATIM) Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Since the Linux kernel and libraries are constantly changing, this manual page may be incorrect or out-of-date. The author(s) assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. The author(s) may not have taken the same level of care in the production of this manual, which is licensed free of charge, as they might when working professionally. Formatted or processed versions of this manual, if unaccompanied by the source, must acknowledge the copyright and authors of this work. %%%LICENSE_END References consulted: Linux libc source code Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) 386BSD man pages Modified Mon Mar 29 22:39:41 1993, David Metcalfe Modified Sat Jul 24 21:38:42 1993, Rik Faith (faithcs.unc.edu) Modified Sun Dec 17 18:35:06 2000, Joseph S. Myers |