fcvt(3) - f39

1ecvt(3)                    Library Functions Manual                    ecvt(3)
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NAME

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

9       Standard C library (libc, -lc)
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SYNOPSIS

12       #include <stdlib.h>
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14       [[deprecated]] char *ecvt(double number, int ndigits,
15                                 int *restrict decpt, int *restrict sign);
16       [[deprecated]] char *fcvt(double number, int ndigits,
17                                 int *restrict decpt, int *restrict sign);
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19   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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21       ecvt(), fcvt():
22           Since glibc 2.17
23               (_XOPEN_SOURCE >= 500 && ! (_POSIX_C_SOURCE >= 200809L))
24                   || /* glibc >= 2.20 */ _DEFAULT_SOURCE
25                   || /* glibc <= 2.19 */ _SVID_SOURCE
26           glibc 2.12 to glibc 2.16:
27               (_XOPEN_SOURCE >= 500 && ! (_POSIX_C_SOURCE >= 200112L))
28                   || _SVID_SOURCE
29           Before glibc 2.12:
30               _SVID_SOURCE || _XOPEN_SOURCE >= 500
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DESCRIPTION

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

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

54       For an  explanation  of  the  terms  used  in  this  section,  see  at‐
55       tributes(7).
56
57       ┌────────────────────────────────┬───────────────┬─────────────────────┐
58       │Interface                       │ Attribute     │ Value               │
59       ├────────────────────────────────┼───────────────┼─────────────────────┤
60       │ecvt()                          │ Thread safety │ MT-Unsafe race:ecvt │
61       ├────────────────────────────────┼───────────────┼─────────────────────┤
62       │fcvt()                          │ Thread safety │ MT-Unsafe race:fcvt │
63       └────────────────────────────────┴───────────────┴─────────────────────┘
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STANDARDS

66       None.
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HISTORY

69       SVr2;  marked  as  LEGACY  in  POSIX.1-2001.   POSIX.1-2008 removes the
70       specifications of ecvt() and fcvt(), recommending the use of sprintf(3)
71       instead (though snprintf(3) may be preferable).
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NOTES

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