update book code

eBook/exercises/chapter_8/map_days.go

@@ -0,0 +1,35 @@
+// map_days.go
+package main
+
+import (
+	"fmt"
+)
+
+var Days = map[int]string{1:"monday", 
+						  2:"tuesday",
+						  3: "wednesday",
+						  4: "thursday",
+						  5: "friday",
+						  6: "saturday",
+						  7: "sunday"}
+
+func main() {
+	fmt.Println(Days)
+	// fmt.Printf("%v", Days)
+	flagHolliday := false
+	for k, v := range Days {
+		if v == "thursday" || v == "holliday" {
+			fmt.Println(v, " is the ", k , "th day in the week")
+			if v == "holliday" {
+				flagHolliday = true
+			}
+		}
+	}
+	if !flagHolliday {
+		fmt.Println("holliday is not a day!")
+	}
+}
+/* Output:
+thursday  is the  4 th day in the week
+holliday is not a day!
+*/