ecvt_r, fcvt_r, qecvt_r, qfcvt_r - convert a floating-point number to a string

#include <stdlib.h>

int ecvt_r(double number, int ndigits, int *decpt,
 int *sign, char *buf, size_t len);

int fcvt_r(double number, int ndigits, int *decpt,
 int *sign, char *buf, size_t len);

int qecvt_r(long double number, int ndigits, int *decpt,
 int *sign, char *buf, size_t len);

int qfcvt_r(long double number, int ndigits, int *decpt,
 int *sign, char *buf, size_t len);

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

The functions ecvt_r(), fcvt_r(), qecvt_r(), and qfcvt_r() are identical to ecvt(3), fcvt(3), qecvt(3), and qfcvt(3), respectively, except that they do not return their result in a static buffer, but instead use the supplied buf of size len. See ecvt(3) and qecvt(3).

These functions return 0 on success, and -1 otherwise.

ecvt(3), qecvt(3), sprintf(3)