add: constants exercises

10-constants/exercises/06-no-conversions-allowed/solution/main.go

@@ -0,0 +1,28 @@
+// 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"
+	"time"
+)
+
+func main() {
+	// hours's type is time.Duration
+	// but later's type was int
+	// now, `later` is typeless
+	//
+	// time.Duration's underlying type is int64
+	// and, `later` is numeric typeless value
+	// so, they can be multiplied
+	const later = 10
+
+	hours, _ := time.ParseDuration("1h")
+
+	fmt.Printf("%s later...\n", hours*later)
+}