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)):


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:

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)

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