key_defined(3X)

💖 key_defined — the "wait, what key is that string even?" decoder ring 💖

okay bestie, so this is a page from the ncurses manual, section 3X — the library calls section. It's called key_defined(3X) and honestly? It's giving detective energy. Let's get into it. 🕵️♀️✨

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✨ NAME ✨

key_defined — obtain key code for an ncurses function key definition

Like. You hand it a string, and it tells you which function key that string is bound to. That's the whole job. Iconic, tbh. 💅

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🎀 SYNOPSIS 🎀

#include <curses.h>

int key_defined(const char * definition);

yes you gotta include <curses.h> first, that's non-negotiable bestie. 🙈

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🦋 DESCRIPTION 🦋

So key_defined is an ncurses extension — meaning it's a little extra that ncurses added on top, not vanilla curses, iykyk. What it does: it lets a curses application figure out the function key code — if any — that the string definition is bound to.

That's it. That's the vibe check. You give it a string, it tells you the key code. 🎯

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🌸 RETURN VALUE 🌸

Here's the tea, and there are three possible outcomes:

• If definition is bound to something, you get back the first key code it's bound to. 🥇
• If it's bound to nothing at all, you get back 0. 🫥
• If definition is a prefix of some other bound definition, you get back -1. 😭 (no exact match, just a teaser)

lowkey important: 0 and -1 mean very different things here. Don't treat them like the same "nope". 💀

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⭐ EXTENSIONS ⭐

key_defined is an ncurses extension. (yes, we said it in DESCRIPTION too — it's that serious, it gets its own section. periodt. 👑)

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🌈 PORTABILITY 🌈

if you're writing code that uses ncurses extensions, bestie, you should condition their use on the visibility of the NCURSES_VERSION preprocessor macro. Basically: check that macro exists before you go using the fancy extension, so your code doesn't get humbled on a system that isn't ncurses. 🧚

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💜 AUTHORS 💜

Thomas Dickey

(shoutout to the legend himself 🫶)

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💅 SEE ALSO 💅

• curses(3X)
• define_key(3X)
• keybound(3X)
• keyok(3X)

go read those next, they're all part of the same little key-binding friend group 🍓

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k that's the whole page!! this was ncurses 6.6, dated 2025-10-04, and it's the key_defined(3X) page — mwah, go forth and decode your keys ✨🎀💖