Golang : Accept any number of function arguments with three dots(...)



Tags : golang average three-dots variadic-parameter

There are times when we need to create functions that are able to accept any number of arguments(a.k.a trailing arguments) during runtime. In Golang, this can be achieved with the three dots or better known as the variadic parameter. For instance, to calculate average value of a given range of numbers. Instead of hard coding the number of arguments to be accepted, you can make your function to be more robust and accept multiple arguments during run time.

For example:

 package main

 import (
  "fmt"
 )

 func avg(rest ...float64) float64 { //<----- here!
  sum := 0.0
  for _, num := range rest {
 sum += num
  }
  return float64(sum) / float64(len(rest))
 }

 func main() {
  fmt.Printf("%0.2f\n", avg(1, 2))
  fmt.Printf("%0.2f\n", avg(1, 2, 3, 4, 5, 6, 7, 8, 9))
  fmt.Printf("%0.2f\n", avg(99, 98, 87, 110, 121, 2))
 }

Output:

1.50

5.00

86.17

Another example to accept any number of string arguments to make a new slice:

 package main

 import (
 "fmt"
 )

 func makeSlice(elements ...string) []string {
 var strSlice []string
 for _, str := range elements {
 strSlice = append(strSlice, str)
 }
 return strSlice
 }

 func main() {
 fmt.Println(makeSlice("abc", "def"))
 fmt.Println(makeSlice("abc", "def", "ghi"))
 fmt.Println(makeSlice("abc", "def", "xyz", "123"))
 fmt.Println(makeSlice("abc"))
 }

Output:

[abc def]

[abc def ghi]

[abc def xyz 123]

[abc]

Happy coding!

References:

http://stackoverflow.com/questions/19238143/does-golang-support-arguments

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  See also : Golang : automatically figure out array length(size) with three dots



Tags : golang average three-dots variadic-parameter

By Adam Ng

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