add 04.4.md translate for ch 4.4

eBook/examples/chapter_4/function_calls_function.go

@@ -0,0 +1,15 @@
+package main
+var a string
+func main() {
+	a = "G"
+	print(a)
+	f1()
+}
+func f1() {
+	a := "O"
+	print(a)
+	f2()
+}
+func f2() {
+	print(a)
+}

eBook/examples/chapter_4/global_scope.go

@@ -0,0 +1,14 @@
+package main
+var a = "G"
+func main() {
+	n()
+	m()
+	n()
+}
+func n() {
+	print(a)
+}
+func m() {
+	a = "O"
+	print(a)
+}

eBook/examples/chapter_4/goos.go

@@ -0,0 +1,11 @@
+package main
+import (
+	"fmt"
+	"os"
+)
+func main() {
+	var goos string = os.Getenv("GOOS")
+	fmt.Printf("The operating system is: %s\n", goos)
+	path := os.Getenv("PATH")
+	fmt.Printf("Path is %s\n", path)
+}

eBook/examples/chapter_4/init.go

@@ -0,0 +1,6 @@
+package trans
+import "math"
+var Pi float64
+func init() {
+	Pi = 4 * math.Atan(1) // init() function computes Pi
+}

eBook/examples/chapter_4/local_scope.go

@@ -0,0 +1,12 @@
+package main
+var a = "G"
+func main() {
+	n()
+	m()
+	n()
+}
+func n() { print(a) }
+func m() {
+	a := "O"
+	print(a)
+}

eBook/examples/chapter_4/user_init.go

@@ -0,0 +1,9 @@
+package main
+import (
+	"fmt"
+	"./trans"
+)
+var twoPi = 2 * trans.Pi
+func main() {
+	fmt.Printf("2*Pi = %g\n", twoPi) // 2*Pi = 6.283185307179586
+}