qux

Qux is a metasyntactic variable used in computer science and programming to serve as a placeholder name in examples and documentation. It has no intrinsic meaning and is not reserved by any programming language; it is simply a stand‑in to illustrate syntax, function calls, or data flow.

In practice, qux commonly appears after other placeholders such as foo, bar, and baz, especially when several placeholders are needed. It is used across languages and paradigms and can serve as a variable name, a function name, or an object identifier in sample code. Because its meaning is deliberately non-specific, authors can substitute different names without altering the illustrative purpose. For example: def qux(a, b, c): return a + b + c.

Qux is part of a family of metasyntactic variables used to demonstrate code and algorithms. Common companions include foo, bar, baz, qux, quux, and quuz. The exact origin of these placeholders is not definitively known; they have been propagated through textbooks, tutorials, and online communities as neutral stand-ins.

See also: metasyntactic variable, placeholder, foo, bar, baz, quux, quuz.