SIMPLE SOLUTIONS

# ECVT(3) - man page online | library functions

Convert a floating-point number to a string.

Chapter
2015-03-02
```ECVT(3)                             Linux Programmer's Manual                             ECVT(3)

NAME
ecvt, fcvt - convert a floating-point number to a string

SYNOPSIS
#include <stdlib.h>

char *ecvt(double number, int ndigits, int *decpt, int *sign);

char *fcvt(double number, int ndigits, int *decpt, int *sign);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

ecvt(), fcvt():
Since glibc 2.12:
_SVID_SOURCE ||
(_XOPEN_SOURCE >= 500 ||
_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED) &&
!(_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600)
Before glibc 2.12:
_SVID_SOURCE || _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED

DESCRIPTION
The ecvt() function converts number to a null-terminated string of ndigits digits (where
ndigits is reduced to a system-specific limit determined by the precision of a double),
and returns a pointer to the string.  The high-order digit is nonzero, unless number is
zero.  The low order digit is rounded.  The string itself does not contain a decimal
point; however, the position of the decimal point relative to the start of the string is
stored in *decpt.  A negative value for *decpt means that the decimal point is to the left
of the start of the string.  If the sign of number is negative, *sign is set to a nonzero
value, otherwise it is set to 0.  If number is zero, it is unspecified whether *decpt is 0
or 1.

The fcvt() function is identical to ecvt(), except that ndigits specifies the number of
digits after the decimal point.

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

ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).

┌──────────┬───────────────┬─────────────────────┐
│Interface │ Attribute     │ Value               │
├──────────┼───────────────┼─────────────────────┤
│ecvt()    │ Thread safety │ MT-Unsafe race:ecvt │
├──────────┼───────────────┼─────────────────────┤
│fcvt()    │ Thread safety │ MT-Unsafe race:fcvt │
└──────────┴───────────────┴─────────────────────┘
CONFORMING TO
SVr2; marked as LEGACY in POSIX.1-2001.  POSIX.1-2008 removes the specifications of ecvt()
and fcvt(), recommending the use of sprintf(3) instead (though snprintf(3) may be prefer‐
able).

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