1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
3 .\" %%%LICENSE_START(VERBATIM)
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9 .\" manual under the conditions for verbatim copying, provided that the
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13 .\" Since the Linux kernel and libraries are constantly changing, this
14 .\" manual page may be incorrect or out-of-date. The author(s) assume no
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18 .\" which is licensed free of charge, as they might when working
21 .\" Formatted or processed versions of this manual, if unaccompanied by
22 .\" the source, must acknowledge the copyright and authors of this work.
25 .\" References consulted:
26 .\" Linux libc source code
27 .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
29 .\" Modified Sat Jul 24 19:40:39 1993 by Rik Faith (faith@cs.unc.edu)
30 .\" Modified Fri Jun 25 12:10:47 1999 by Andries Brouwer (aeb@cwi.nl)
32 .TH ECVT 3 2016-03-15 "" "Linux Programmer's Manual"
34 ecvt, fcvt \- convert a floating-point number to a string
36 .B #include <stdlib.h>
38 .BI "char *ecvt(double " number ", int " ndigits ", int *" decpt ,
41 .BI "char *fcvt(double " number ", int " ndigits ", int *" decpt ,
45 Feature Test Macro Requirements for glibc (see
46 .BR feature_test_macros (7)):
57 (_XOPEN_SOURCE\ >=\ 500) ! (_POSIX_C_SOURCE\ >=\ 200112L)
58 || /* Glibc since 2.19: */ _DEFAULT_SOURCE
59 || /* Glibc versions <= 2.19: */ _SVID_SOURCE
63 _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500
64 .\" || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
71 function converts \fInumber\fP to a null-terminated
72 string of \fIndigits\fP digits (where \fIndigits\fP is reduced to a
73 system-specific limit determined by the precision of a
75 and returns a pointer to the string.
76 The high-order digit is nonzero, unless
79 The low order digit is rounded.
80 The string itself does not contain a decimal point; however,
81 the position of the decimal point relative to the start of the string
82 is stored in \fI*decpt\fP.
83 A negative value for \fI*decpt\fP means that
84 the decimal point is to the left of the start of the string.
86 \fInumber\fP is negative, \fI*sign\fP is set to a nonzero value,
87 otherwise it is set to 0.
90 is zero, it is unspecified whether \fI*decpt\fP is 0 or 1.
94 function is identical to
97 \fIndigits\fP specifies the number of digits after the decimal point.
103 functions return a pointer to a
104 static string containing the ASCII representation of \fInumber\fP.
105 The static string is overwritten by each call to
110 For an explanation of the terms used in this section, see
116 Interface Attribute Value
119 T} Thread safety MT-Unsafe race:ecvt
122 T} Thread safety MT-Unsafe race:fcvt
126 marked as LEGACY in POSIX.1-2001.
127 POSIX.1-2008 removes the specifications of
131 recommending the use of
137 .\" Linux libc4 and libc5 specified the type of
141 Not all locales use a point as the radix character ("decimal point").