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+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 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 (faith@cs.unc.edu)
+.\" Modified Sun Dec 17 18:35:06 2000, Joseph S. Myers
+.\"
+.TH atoi 3 2023-07-20 "Linux man-pages 6.05.01"
+.SH NAME
+atoi, atol, atoll \- convert a string to an integer
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.PP
+.BI "int atoi(const char *" nptr );
+.BI "long atol(const char *" nptr );
+.BI "long long atoll(const char *" nptr );
+.fi
+.PP
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.PP
+.BR atoll ():
+.nf
+ _ISOC99_SOURCE
+ || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR atoi ()
+function converts the initial portion of the string
+pointed to by \fInptr\fP to
+.IR int .
+The behavior is the same as
+.PP
+.in +4n
+.EX
+strtol(nptr, NULL, 10);
+.EE
+.in
+.PP
+except that
+.BR atoi ()
+does not detect errors.
+.PP
+The
+.BR atol ()
+and
+.BR atoll ()
+functions behave the same as
+.BR atoi (),
+except that they convert the initial portion of the
+string to their return type of \fIlong\fP or \fIlong long\fP.
+.SH RETURN VALUE
+The converted value or 0 on error.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface Attribute Value
+T{
+.na
+.nh
+.BR atoi (),
+.BR atol (),
+.BR atoll ()
+T} Thread safety MT-Safe locale
+.TE
+.sp 1
+.SH VERSIONS
+POSIX.1 leaves the return value of
+.BR atoi ()
+on error unspecified.
+On glibc, musl libc, and uClibc, 0 is returned on error.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001, SVr4, 4.3BSD.
+.PP
+C89 and
+POSIX.1-1996 include the functions
+.BR atoi ()
+and
+.BR atol ()
+only.
+.\" .SH NOTES
+.\" Linux libc provided
+.\" .BR atoq ()
+.\" as an obsolete name for
+.\" .BR atoll ();
+.\" .BR atoq ()
+.\" is not provided by glibc.
+.\" The
+.\" .BR atoll ()
+.\" function is present since glibc 2.0.2, but
+.\" not in libc4 or libc5.
+.SH BUGS
+.I 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
+.BR strtol ()
+and
+.BR strtoul ()
+family of functions in new programs.
+.SH SEE ALSO
+.BR atof (3),
+.BR strtod (3),
+.BR strtol (3),
+.BR strtoul (3)