add: switch statement exercises

12-switch/exercises/05-days-in-month/main.go

@@ -0,0 +1,62 @@
+// 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"
+	"strings"
+	"time"
+)
+
+// ---------------------------------------------------------
+// EXERCISE: Days in a Month
+//
+//  Refactor the previous exercise from the if statement
+//  section.
+//
+//  "Print the number of days in a given month."
+//
+//  Use a switch statement instead of if statements.
+// ---------------------------------------------------------
+
+func main() {
+	if len(os.Args) != 2 {
+		fmt.Println("Give me a month name")
+		return
+	}
+
+	year := time.Now().Year()
+	leap := year%4 == 0 && (year%100 != 0 || year%400 == 0)
+
+	days, month := 28, os.Args[1]
+
+	if m := strings.ToLower(month); m == "april" ||
+		m == "june" ||
+		m == "september" ||
+		m == "november" {
+		days = 30
+	} else if m == "january" ||
+		m == "march" ||
+		m == "may" ||
+		m == "july" ||
+		m == "august" ||
+		m == "october" ||
+		m == "december" {
+		days = 31
+	} else if m == "february" {
+		if leap {
+			days = 29
+		}
+	} else {
+		fmt.Printf("%q is not a month.\n", month)
+		return
+	}
+
+	fmt.Printf("%q has %d days.\n", month, days)
+}