qecvt(3)

✨ qecvt — convert a floating-point number to a string ✨

okay bestie, pull up a chair 🫶 this one's from the Library Functions Manual section 3 of the manual, and it is lowkey a fossil. but we're gonna learn it anyway because i love you 💖

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🦋 NAME 🦋

qecvt, qfcvt, qgcvt — convert a floating-point number to a string

📚 LIBRARY 📚

Standard C library (libc, -lc)

🌸 SYNOPSIS 🌸

#include <stdlib.h>

[[deprecated]] char *qecvt(long double number, int ndigits,
                           int *restrict decpt, int *restrict sign);
[[deprecated]] char *qfcvt(long double number, int ndigits,
                           int *restrict decpt, int *restrict sign);
[[deprecated]] char *qgcvt(long double number, int ndigit, char *buf);

🎀 Feature Test Macro Requirements for glibc 🎀

(if you don't know what a feature test macro is, go read feature_test_macros(7), it's giving ✨required reading✨)

• qecvt(), qfcvt(), qgcvt():
  • Since glibc 2.19:
    • _DEFAULT_SOURCE
  • In glibc up to and including 2.19:
    • _SVID_SOURCE

bestie. all three of these are [[deprecated]]. that's in the synopsis, not me being dramatic. 💀

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💅 DESCRIPTION 💅

okay so here's the tea, and it's honestly so simple it's almost funny:

The functions qecvt(), qfcvt(), and qgcvt() are identical to ecvt(3), fcvt(3), and gcvt(3) respectively, except that they use a long double argument number. 😌

That's it. That's the whole plot. The q is just the "long double era" version of the same trio. Go see ecvt(3) and gcvt(3) for the actual vibes of what they do.

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🧚 ATTRIBUTES 🧚

For an explanation of the terms used in this section, see attributes(7). (iykyk 🌈)

• qecvt() — Thread safety: MT-Unsafe race:qecvt
• qfcvt() — Thread safety: MT-Unsafe race:qfcvt
• qgcvt() — Thread safety: MT-Safe

not qecvt() and qfcvt() being unsafe in a race while qgcvt() is out here being the well-behaved one 😭 slay i guess, qgcvt().

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👑 STANDARDS 👑

None.

like. none. the standards committee said "who?" 🙈

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💀 HISTORY 💀

SVr4, SunOS, GNU.

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

periodt. 💅 if you were about to use these in new code: don't, bestie. use snprintf(3). i'm literally begging 🥺

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🔥 SEE ALSO 🔥

• ecvt(3)
• ecvt_r(3)
• gcvt(3)
• sprintf(3)

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and that's the whole page!! you absolutely ate that read, no cap 🎀 this was Linux man-pages 6.20, dated 2026-02-08, and it lives on your system as qecvt(3). go forth and use snprintf(3) instead, mwah 💖🦋✨