1ATOF(3P)                   POSIX Programmer's Manual                  ATOF(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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11

NAME

13       atof — convert a string to a double-precision number
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SYNOPSIS

16       #include <stdlib.h>
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18       double atof(const char *str);
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DESCRIPTION

21       The functionality described on this reference page is aligned with  the
22       ISO C  standard.  Any  conflict between the requirements described here
23       and the ISO C standard is unintentional. This  volume  of  POSIX.1‐2008
24       defers to the ISO C standard.
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26       The call atof(str) shall be equivalent to:
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28           strtod(str,(char **)NULL),
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30       except  that  the handling of errors may differ. If the value cannot be
31       represented, the behavior is undefined.
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RETURN VALUE

34       The atof() function shall return the converted value if the  value  can
35       be represented.
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ERRORS

38       No errors are defined.
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40       The following sections are informative.
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EXAMPLES

43       None.
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APPLICATION USAGE

46       The  atof() function is subsumed by strtod() but is retained because it
47       is used extensively in existing code. If the number is not known to  be
48       in  range,  strtod()  should  be used because atof() is not required to
49       perform any error checking.
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RATIONALE

52       None.
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FUTURE DIRECTIONS

55       None.
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SEE ALSO

58       strtod()
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60       The Base Definitions volume of POSIX.1‐2008, <stdlib.h>
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63       Portions of this text are reprinted and reproduced in  electronic  form
64       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
65       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
66       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
67       cal and Electronics Engineers,  Inc  and  The  Open  Group.   (This  is
68       POSIX.1-2008  with  the  2013  Technical Corrigendum 1 applied.) In the
69       event of any discrepancy between this version and the original IEEE and
70       The  Open Group Standard, the original IEEE and The Open Group Standard
71       is the referee document. The original Standard can be  obtained  online
72       at http://www.unix.org/online.html .
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74       Any  typographical  or  formatting  errors that appear in this page are
75       most likely to have been introduced during the conversion of the source
76       files  to  man page format. To report such errors, see https://www.ker‐
77       nel.org/doc/man-pages/reporting_bugs.html .
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81IEEE/The Open Group                  2013                             ATOF(3P)
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