man3/atoi.3

   1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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  25 .\" References consulted:
  26 .\"     Linux libc source code
  27 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
  28 .\"     386BSD man pages
  29 .\" Modified Mon Mar 29 22:39:41 1993, David Metcalfe
  30 .\" Modified Sat Jul 24 21:38:42 1993, Rik Faith (faith@cs.unc.edu)
  31 .\" Modified Sun Dec 17 18:35:06 2000, Joseph S. Myers
  32 .\"
  33 .TH ATOI 3  2016-03-15 "GNU" "Linux Programmer's Manual"
  34 .SH NAME
  35 atoi, atol, atoll \- convert a string to an integer
  36 .SH SYNOPSIS
  37 .nf
  38 .B #include <stdlib.h>
  39 .PP
  40 .BI "int atoi(const char *" nptr );
  41 .BI "long atol(const char *" nptr );
  42 .BI "long long atoll(const char *" nptr );
  43 .fi
  44 .PP
  45 .in -4n
  46 Feature Test Macro Requirements for glibc (see
  47 .BR feature_test_macros (7)):
  48 .in
  49 .PP
  50 .ad l
  51 .BR atoll ():
  52 .RS 4
  53 _ISOC99_SOURCE ||
  54     || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  55 .RE
  56 .ad
  57 .SH DESCRIPTION
  58 The
  59 .BR atoi ()
  60 function converts the initial portion of the string
  61 pointed to by \fInptr\fP to
  62 .IR int .
  63 The behavior is the same as
  64 .PP
  65 .in +4n
  66 .EX
  67 strtol(nptr, NULL, 10);
  68 .EE
  69 .in
  70 .PP
  71 except that
  72 .BR atoi ()
  73 does not detect errors.
  74 .PP
  75 The
  76 .BR atol ()
  77 and
  78 .BR atoll ()
  79 functions behave the same as
  80 .BR atoi (),
  81 except that they convert the initial portion of the
  82 string to their return type of \fIlong\fP or \fIlong long\fP.
  83 .SH RETURN VALUE
  84 The converted value.
  85 .SH ATTRIBUTES
  86 For an explanation of the terms used in this section, see
  87 .BR attributes (7).
  88 .TS
  89 allbox;
  90 lbw23 lb lb
  91 l l l.
  92 Interface       Attribute       Value
  93 T{
  94 .BR atoi (),
  95 .BR atol (),
  96 .BR atoll ()
  97 T}      Thread safety   MT-Safe locale
  98 .TE
  99 .SH CONFORMING TO
 100 POSIX.1-2001, POSIX.1-2008, C99, SVr4, 4.3BSD.
 101 C89 and
 102 POSIX.1-1996 include the functions
 103 .BR atoi ()
 104 and
 105 .BR atol ()
 106 only.
 107 .SH NOTES
 108 Linux libc provided
 109 .BR atoq ()
 110 as an obsolete name for
 111 .BR atoll ();
 112 .BR atoq ()
 113 is not provided by glibc.
 114 .\" The
 115 .\" .BR atoll ()
 116 .\" function is present in glibc 2 since version 2.0.2, but
 117 .\" not in libc4 or libc5.
 118 .SH SEE ALSO
 119 .BR atof (3),
 120 .BR strtod (3),
 121 .BR strtol (3),
 122 .BR strtoul (3)