Linux manual pages Section 3  

Name

atoi, atol, atoll, atoq — 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);
 
long long atoq( const char *nptr);
 
[Note] Note
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
atoll():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE;
or cc -std=c99

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, (char **) 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. atoq() is an obsolete name for atoll().

RETURN VALUE

The converted value.

CONFORMING TO

SVr4, POSIX.1-2001, 4.3BSD, C99. C89 and POSIX.1-1996 include the functions atoi() and atol() only. atoq() is a GNU extension.

NOTES

The nonstandard atoq() function is not present in libc 4.6.27 or glibc 2, but is present in libc5 and libc 4.7 (though only as an inline function in <stdlib.h> until libc 5.4.44). The atoll() function is present in glibc 2 since version 2.0.2, but not in libc4 or libc5.

SEE ALSO

atof(3), strtod(3), strtol(3), strtoul(3)

COLOPHON

This page is part of release 3.24 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.


  Copyright 1993 David Metcalfe (davidprism.demon.co.uk)

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manual page may be incorrect or out-of-date.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.

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