ecvt(3) - f34

1ECVT(3)                    Linux Programmer's Manual                   ECVT(3)
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NAME

6       ecvt, fcvt - convert a floating-point number to a string
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SYNOPSIS

9       #include <stdlib.h>
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11       char *ecvt(double number, int ndigits, int *decpt, int *sign);
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13       char *fcvt(double number, int ndigits, int *decpt, int *sign);
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15   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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17       ecvt(), fcvt():
18           Since glibc 2.12:
19               (_XOPEN_SOURCE >= 500) ! (_POSIX_C_SOURCE >= 200112L)
20                   || /* Glibc since 2.19: */ _DEFAULT_SOURCE
21                   || /* Glibc versions <= 2.19: */ _SVID_SOURCE
22           Before glibc 2.12:
23               _SVID_SOURCE || _XOPEN_SOURCE >= 500
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DESCRIPTION

26       The  ecvt()  function  converts  number  to a null-terminated string of
27       ndigits digits (where ndigits is reduced to a system-specific limit de‐
28       termined  by  the  precision of a double), and returns a pointer to the
29       string.  The high-order digit is nonzero, unless number is  zero.   The
30       low order digit is rounded.  The string itself does not contain a deci‐
31       mal point; however, the position of the decimal point relative  to  the
32       start  of  the string is stored in *decpt.  A negative value for *decpt
33       means that the decimal point is to the left of the start of the string.
34       If  the  sign  of  number is negative, *sign is set to a nonzero value,
35       otherwise it is set to 0.  If number is zero, it is unspecified whether
36       *decpt is 0 or 1.
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38       The  fcvt() function is identical to ecvt(), except that ndigits speci‐
39       fies the number of digits after the decimal point.
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RETURN VALUE

42       Both the ecvt() and fcvt() functions  return  a  pointer  to  a  static
43       string  containing  the  ASCII  representation  of  number.  The static
44       string is overwritten by each call to ecvt() or fcvt().
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ATTRIBUTES

47       For an  explanation  of  the  terms  used  in  this  section,  see  at‐
48       tributes(7).
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50       ┌──────────┬───────────────┬─────────────────────┐
51       │Interface │ Attribute     │ Value               │
52       ├──────────┼───────────────┼─────────────────────┤
53       │ecvt()    │ Thread safety │ MT-Unsafe race:ecvt │
54       ├──────────┼───────────────┼─────────────────────┤
55       │fcvt()    │ Thread safety │ MT-Unsafe race:fcvt │
56       └──────────┴───────────────┴─────────────────────┘

CONFORMING TO

58       SVr2; marked as LEGACY in POSIX.1-2001.  POSIX.1-2008 removes the spec‐
59       ifications of ecvt() and fcvt(), recommending the use of sprintf(3) in‐
60       stead (though snprintf(3) may be preferable).
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NOTES

63       Not all locales use a point as the radix character ("decimal point").
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COLOPHON

69       This  page  is  part of release 5.10 of the Linux man-pages project.  A
70       description of the project, information about reporting bugs,  and  the
71       latest     version     of     this    page,    can    be    found    at
72       https://www.kernel.org/doc/man-pages/.
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76                                  2016-03-15                           ECVT(3)