GCVT(3) Linux Programmer's Manual GCVT(3)

gcvt - convert a floating-point number to a string

#include <stdlib.h>
char *gcvt(double number, int ndigit, char *buf);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

gcvt():

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

The gcvt() function converts number to a minimal length null-terminated ASCII string and stores the result in buf. It produces ndigit significant digits in either printf(3) F format or E format.

The gcvt() function returns buf.

For an explanation of the terms used in this section, see attributes(7).
Interface Attribute Value
gcvt () Thread safety MT-Safe

Marked as LEGACY in POSIX.1-2001. POSIX.1-2008 removes the specification of gcvt(), recommending the use of sprintf(3) instead (though snprintf(3) may be preferable).

ecvt(3), fcvt(3), sprintf(3)

This page is part of release 5.13 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.
2021-03-22