ecvt(3) Library Functions Manual ecvt(3)

# NAME

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

# LIBRARY

Standard C library (libc, -lc)

# SYNOPSIS

`#include <stdlib.h>`
```[[deprecated]] char *ecvt(double number, int ndigits,
int *restrict decpt, int *restrict sign);
[[deprecated]] char *fcvt(double number, int ndigits,
int *restrict decpt, int *restrict sign);```
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

ecvt(), fcvt():

```    Since glibc 2.17
(_XOPEN_SOURCE >= 500 && ! (_POSIX_C_SOURCE >= 200809L))
|| /* glibc >= 2.20 */ _DEFAULT_SOURCE
|| /* glibc <= 2.19 */ _SVID_SOURCE
glibc 2.12 to glibc 2.16:
(_XOPEN_SOURCE >= 500 && ! (_POSIX_C_SOURCE >= 200112L))
|| _SVID_SOURCE
Before glibc 2.12:
_SVID_SOURCE || _XOPEN_SOURCE >= 500```

# 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

None.

# HISTORY

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 preferable).

# NOTES

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