C's printf is one of the most widely used variadic functions.
There are some functions and predicates which we tend to think of as being able to take any number of parameters – of being of variable arity or variadic.1983, Alan Bundy, The Computer Modelling of Mathematical Reasoning, Academic Press, page 48:
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The variadic functions that increase the valence of the input relation through the addition of a circumstance to the set of its argument-roles can be represented by means of an operator (or rather, a family of operators) ‘Circ’.2004, François Récanati, Literal Meaning, Cambridge University Press, →ISBN, page 109:
However, the real max procedure of Scheme is a variadic procedure, which means that it accepts any positive number of arguments: ¶ (max 5 1 3 8 9 7 2 6 4) => 92006, Nils M. Holm, Sketchy LISP: An Introduction to Functional Programming in Scheme, 2nd edition, Lulu.com, →ISBN, page 53: