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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NAME

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

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

20       The functionality described on this reference page is aligned with  the
21       ISO C  standard.  Any  conflict between the requirements described here
22       and the ISO C standard is unintentional. This  volume  of  POSIX.1‐2017
23       defers to the ISO C standard.
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25       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.1‐2017, <stdlib.h>
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63       Portions of this text are reprinted and reproduced in  electronic  form
64       from  IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
65       table Operating System Interface (POSIX), The Open Group Base  Specifi‐
66       cations  Issue  7, 2018 Edition, Copyright (C) 2018 by the Institute of
67       Electrical and Electronics Engineers, Inc and The Open Group.   In  the
68       event of any discrepancy between this version and the original IEEE and
69       The Open Group Standard, the original IEEE and The Open Group  Standard
70       is  the  referee document. The original Standard can be obtained online
71       at http://www.opengroup.org/unix/online.html .
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73       Any typographical or formatting errors that appear  in  this  page  are
74       most likely to have been introduced during the conversion of the source
75       files to man page format. To report such errors,  see  https://www.ker‐
76       nel.org/doc/man-pages/reporting_bugs.html .
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80IEEE/The Open Group                  2017                             ATOF(3P)
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