update: directory structure

advfuncs/01-variadic-funcs/main.go

@@ -0,0 +1,73 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import "fmt"
+
+func main() {
+	nums := []int{2, 3, 7}
+	fmt.Printf("nums            : %d\n", nums)
+
+	n := avgNoVariadic(nums)
+	fmt.Printf("avgNoVariadic   : %d\n", n)
+
+	n = avg(2, 3, 7)
+	fmt.Printf("avg(2, 3, 7)    : %d\n", n)
+
+	n = avg(2, 3, 7, 8)
+	fmt.Printf("avg(2, 3, 7, 8) : %d\n", n)
+
+	// use ... to pass a slice
+	n = avg(nums...)
+	fmt.Printf("avg(nums...)    : %d\n", n)
+
+	// uses the existing slice
+	double(nums...)
+	fmt.Printf("double(nums...) : %d\n", nums)
+
+	// creates a new slice
+	double(4, 6, 14)
+	fmt.Printf("double(4, 6, 14): %d\n", nums)
+
+	// creates a nil slice
+	fmt.Printf("\nmain.nums       : %p\n", nums)
+	investigate("passes main.nums", nums...)
+	investigate("passes main.nums", nums...)
+	investigate("passes args", 4, 6, 14)
+	investigate("passes args", 4, 6, 14)
+	investigate("no args")
+}
+
+func investigate(msg string, nums ...int) {
+	fmt.Printf("investigate.nums: %12p  ->  %s\n", nums, msg)
+
+	if len(nums) > 0 {
+		fmt.Printf("\tfirst element: %d\n", nums[0])
+	}
+}
+
+func double(nums ...int) {
+	for i := range nums {
+		nums[i] *= 2
+	}
+}
+
+func avg(nums ...int) int {
+	return sum(nums) / len(nums)
+}
+
+func avgNoVariadic(nums []int) int {
+	return sum(nums) / len(nums)
+}
+
+func sum(nums []int) (total int) {
+	for _, n := range nums {
+		total += n
+	}
+	return
+}