Swift 60秒43 - Variadic functions

Posted 2022-11-12

0x00 Lesson

Some functions are ​​variadic​​​, which is a fancy way of saying they accept any number of parameters of the same type. The ​​print()​​​ function is actually ​​variadic​​: if you pass lots of parameters, they are all printed on one line with spaces between them:

print("Haters", "gonna", "hate")

You can make any parameter ​​variadic​​​ by writing ​​...​​​ after its type. So, an ​​Int​​​ parameter is a single integer, whereas ​​Int...​​ is zero or more integers - potentially hundreds.

Inside the function, Swift converts the values that were passed in to an ​​array​​ of integers, so you can loop over them as needed.

To try this out, let’s write a ​​square()​​ function that can square many numbers:

func square(numbers: Int...) 
  for number in numbers 
    print("\\(number) squared is \\(number * number)")
  

Now we can run that with lots of numbers just by passing them in separated by commas:

square(numbers: 1, 2, 3, 4, 5)

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