gcvt(3) Library Functions Manual gcvt(3)

gcvt - convert a floating-point number to a string

Standard C library (libc, -lc)

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


    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

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 removed it, recommending the use of sprintf(3) instead (though snprintf(3) may be preferable).

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

2024-05-02 Linux man-pages 6.9.1