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

       For an explanation of the terms used in this section, see attributes(7).
       ┌─────────────────────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                                                                   │ Attribute     │ Value   │
       ├─────────────────────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │ ecvt_r(), fcvt_r(), qecvt_r(), qfcvt_r()                                    │ Thread safety │ MT-Safe │
       └─────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘

       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).

       Standard C library (libc, -lc)

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

       These functions are obsolete.  Instead, sprintf(3) is recommended.

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

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

Linux man-pages 6.9.1                              2024-05-02                                          ecvt_r(3)

       GNU.

#include<stdlib.h>[[deprecated]]intecvt_r(doublenumber,intndigits,int*restrictdecpt,int*restrictsign,char*restrictbuf,size_tlen);[[deprecated]]intfcvt_r(doublenumber,intndigits,int*restrictdecpt,int*restrictsign,char*restrictbuf,size_tlen);[[deprecated]]intqecvt_r(longdoublenumber,intndigits,int*restrictdecpt,int*restrictsign,char*restrictbuf,size_tlen);[[deprecated]]intqfcvt_r(longdoublenumber,intndigits,int*restrictdecpt,int*restrictsign,char*restrictbuf,size_tlen);

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

       ecvt_r(), fcvt_r(), qecvt_r(), qfcvt_r():
           /* glibc >= 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE