adding documentation around range and a slight reference to channels

Author: symonk

README.md

@@ -22,3 +22,4 @@ all the examples `Run` functions sequentially in line with the table of contents
 * [08 - Arrays](arrays/main.go)
 * [09 - Slices](slices/main.go)
 * [10 - Maps](maps/main.go)
+* [11 - Range](ranges/main.go)

ranges/main.go

@@ -6,7 +6,18 @@ import "fmt"
 Range iterates over elements in a variety of data structures.
 */
 func Run() {
+	// range over array & slice returns an index and the element.
 	rangeOverArray()
+	rangeOverSlice()
+
+	// range on a map returns both the key and value
+	rangeOverMap()
+	// Range on strings returns the rune(s)
+	rangeOnStrings()
+
+	// Range over channels.  References the channels directory if they are a
+	// new concept to you!
+	rangeOverChannel()
 }
 
 func rangeOverArray() {
@@ -17,3 +28,59 @@ func rangeOverArray() {
 	}
 	fmt.Println(total) // 15
 }
+
+func rangeOverSlice() {
+	slice := []string{"one", "two"}
+	for index, element := range slice {
+		fmt.Printf("index: %d was %s\n", index, element)
+	}
+}
+
+func rangeOverMap() {
+	m := map[string]string{"one": "One", "two": "Two"}
+	for key, value := range m {
+		fmt.Printf("Key %s, Value %s\n", key, value)
+	}
+}
+
+func rangeOnStrings() {
+	word := "hello"
+	for index, theRune := range word {
+		fmt.Println(index, theRune)
+		/*
+			The index of the characters, as well as the unicode code point for each one.
+			0 104
+			1 101
+			2 108
+			3 108
+			4 111
+		*/
+	}
+}
+
+func rangeOverChannel() {
+	/*
+		Note: if you are following in order, you aren't aware of channels yet but just take this
+		as-is for now, it likely won't make sense.  Reference `channels` to understand more there
+		first
+	*/
+
+	// This is a buffered channel, with a buffer size of 3
+	myChan := make(chan string, 3)
+	// push three values in
+	myChan <- "one"
+	myChan <- "two"
+	myChan <- "three"
+
+	// Close the channel to signal, no more values will be sent
+	close(myChan)
+	for element := range myChan {
+		fmt.Println(element)
+		/*
+			"one"
+			"two"
+			"three"
+		*/
+	}
+
+}