1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
3 .\" %%%LICENSE_START(VERBATIM)
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13 .\" Since the Linux kernel and libraries are constantly changing, this
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21 .\" Formatted or processed versions of this manual, if unaccompanied by
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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 2013-07-04 "" "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)):
58 (_XOPEN_SOURCE\ >=\ 500 ||
59 _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED) &&
60 !(_POSIX_C_SOURCE\ >=\ 200112L || _XOPEN_SOURCE\ >=\ 600)
64 _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
65 _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
72 function converts \fInumber\fP to a null-terminated
73 string of \fIndigits\fP digits (where \fIndigits\fP is reduced to a
74 system-specific limit determined by the precision of a
76 and returns a pointer to the string.
77 The high-order digit is nonzero, unless
80 The low order digit is rounded.
81 The string itself does not contain a decimal point; however,
82 the position of the decimal point relative to the start of the string
83 is stored in \fI*decpt\fP.
84 A negative value for \fI*decpt\fP means that
85 the decimal point is to the left of the start of the string.
87 \fInumber\fP is negative, \fI*sign\fP is set to a nonzero value,
88 otherwise it is set to 0.
91 is zero, it is unspecified whether \fI*decpt\fP is 0 or 1.
95 function is identical to
98 \fIndigits\fP specifies the number of digits after the decimal point.
104 functions return a pointer to a
105 static string containing the ASCII representation of \fInumber\fP.
106 The static string is overwritten by each call to
111 .SS Multithreading (see pthreads(7))
116 functions are not thread-safe.
119 marked as LEGACY in POSIX.1-2001.
120 POSIX.1-2008 removes the specifications of
124 recommending the use of
130 .\" Linux libc4 and libc5 specified the type of
134 Not all locales use a point as the radix character ("decimal point").