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Flimzy
Asked: 2020-12-11 00:16:33 +0800 CST 2020-12-11 00:16:33 +0800 CST

What type is the final parameter in a variadic function?

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I've read about variadic functions :

The final parameter in a function signature may have a type prefixed with .... A function with such a parameter is called variadic and may be invoked with zero or more arguments for that parameter.

Translated:

The final parameter in a function signature can have a type prefixed with .... A function with such a parameter is called a variadic and can be called with zero or more arguments to that parameter.

So, it is valid:

func Zoológico(ación string, animales ...string) {
   // ...
}

But what will be the type of animales? Is it a string, or []string, or something else "special"?

go

1 Answers

  1. Best Answer

    The type of the parameter specified with ...Tshall be of type []Tas specified in the Passing arguments to ... parameters section :

    If fit is variadic with a final parameter pof type ...T, within fthe type of pis equivalent to []T. If fcalled without parameters on p, the value assigned to pis nil. Otherwise, the value passed is a new slice of type []Twith a new underlying array whose elements are the function's arguments, which are to be assignable to T. The length and capacity of the slice is thus the number of arguments associated with pit and can be different at each place of call.

    The original version of this paragraph reads:

    If fis variadic with a final parameter pof type ...T, then within fthe type of pis equivalent to type []T. If fis invoked with no actual arguments for p, the value passed to pis nil. Otherwise, the value passed is a new slice of type []Twith a new underlying array whose successive elements are the actual arguments, which all must be assignable to T. The length and capacity of the slice is therefore the number of arguments bound to pand may differ for each call site.

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