add: for statement loop exercises

13-loops/exercises/04-only-evens/main.go

@@ -0,0 +1,30 @@
+// 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
+
+// ---------------------------------------------------------
+// EXERCISE: Only evens
+//
+//  1. Extend the "Sum up to N" exercise
+//  2. Sum only the even numbers
+//
+// RESTRICTIONS
+//  Skip odd numbers using the `continue` statement
+//
+// EXPECTED OUTPUT
+//  Let's suppose that the user runs it like this:
+//
+//    go run main.go 1 10
+//
+//  Then it should print:
+//
+//    2 + 4 + 6 + 8 + 10 = 30
+// ---------------------------------------------------------
+
+func main() {
+}

13-loops/exercises/04-only-evens/solution/main.go

@@ -0,0 +1,42 @@
+// 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"
+	"os"
+	"strconv"
+)
+
+func main() {
+	if len(os.Args) < 3 {
+		fmt.Println("gimme two numbers")
+		return
+	}
+
+	min, err1 := strconv.Atoi(os.Args[1])
+	max, err2 := strconv.Atoi(os.Args[2])
+	if err1 != nil || err2 != nil || min >= max {
+		fmt.Println("wrong numbers")
+		return
+	}
+
+	var sum int
+	for i := min; i <= max; i++ {
+		if i%2 != 0 {
+			continue
+		}
+		sum += i
+
+		fmt.Print(i)
+		if i != max {
+			fmt.Print(" + ")
+		}
+	}
+	fmt.Printf(" = %d\n", sum)
+}