maps and range

maps.go

@@ -0,0 +1,27 @@
+package main
+
+import "fmt"
+
+func main() {
+
+	m := make(map[string]int)
+
+	m["k1"] = 7
+	m["k2"] = 13
+
+	fmt.Println("map:", m)
+
+	v1 := m["k1"]
+	fmt.Println("v1: ", v1)
+
+	fmt.Println("len:", len(m))
+
+	delete(m, "k2")
+	fmt.Println("map:", m)
+
+	_, prs := m["k2"]
+	fmt.Println("prs:", prs)
+
+	n := map[string]int{"foo": 1, "bar": 2}
+	fmt.Println("map:", n)
+}

range.go

@@ -0,0 +1,32 @@
+package main
+
+import "fmt"
+
+func main() {
+
+	nums := []int{2, 3, 4}
+	sum := 0
+	for _, num := range nums {
+		sum += num
+	}
+	fmt.Println("sum:", sum)
+
+	for i, num := range nums {
+		if num == 3 {
+			fmt.Println("index:", i)
+		}
+	}
+
+	kvs := map[string]string{"a": "apple", "b": "banana"}
+	for k, v := range kvs {
+		fmt.Printf("%s -> %s\n", k, v)
+	}
+
+	for k := range kvs {
+		fmt.Println("key:", k)
+	}
+
+	for i, c := range "go" {
+		fmt.Println(i, c)
+	}
+}