How to Unpack Array as Arguments in Go

Created May 3, 2022 at 22:54

Modified May 3, 2022 at 23:10

Using Variadic Functions

Variadic functions can be called with any number of trailing arguments. Here’s a function that will take an arbitrary number of ints as arguments. For example,

package main

import "fmt"

// Variadic Functions
func sum(args ...int) int {
  total := 0
  for _, v := range args {
    total += v
  }
  return total
}

func main() {
  a := []int{1, 2, 3}

  t := sum(a...)
  fmt.Println(t)

  t = sum(2, 3, 4)
  fmt.Println(t)
}

6
9

Using Reflection

If you really want to do this dynamically on a function of fixed number of arguments, you can use reflection:

package main

import (
  "fmt"
  "reflect"
)

func sum(a, b, c int) int {
  return a + b + c
}

func main() {
  a := []int{1, 2, 3}

  var args []reflect.Value
  for _, v := range a {
    args = append(args, reflect.ValueOf(v))
  }
  fun := reflect.ValueOf(sum)
  result := fun.Call(args)
  sum := result[0].Interface().(int)
  fmt.Println(sum)
}