Initial commit

11-if/04-short-if/04-scope-shadowing/01-shadowing/main.go

@@ -0,0 +1,37 @@
+// 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"
+	"strconv"
+)
+
+func main() {
+	// UNCOMMENT THIS TO SEE IT IN ACTION:
+	// var n int
+
+	if a := os.Args; len(a) != 2 {
+		fmt.Println("Give me a number.")
+	} else if n, err := strconv.Atoi(a[1]); err != nil {
+		// else if here shadows the main func's n
+		// variable and it declares it own
+		// with the same name: n
+
+		fmt.Printf("Cannot convert %q.\n", a[1])
+	} else {
+		fmt.Printf("%s * 2 is %d\n", a[1], n*2)
+	}
+
+	// n here belongs to the main func
+	// not to the if statement above
+
+	// UNCOMMENT ALSO LINES BELOW TO SEE IT IN ACTION:
+	// fmt.Printf("n is %d. 👻 👻 👻 - you've been shadowed ;-)", n)
+}

11-if/04-short-if/04-scope-shadowing/02-shadowing-solution/main.go

@@ -0,0 +1,44 @@
+// 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"
+	"strconv"
+)
+
+func main() {
+	// n and err belongs to the main function now
+	// not only to the if statement below
+	var (
+		n   int
+		err error
+	)
+
+	if a := os.Args; len(a) != 2 {
+		fmt.Println("Give me a number.")
+	} else if n, err = strconv.Atoi(a[1]); err != nil {
+		// here else if uses the main func's n and err
+		// variables instead of its own
+
+		fmt.Printf("Cannot convert %q.\n", a[1])
+	} else {
+		// assigns the result back into main func's
+		// n variable
+		n *= 2
+
+		fmt.Printf("%s * 2 is %d\n", a[1], n)
+	}
+
+	// if statement has calculated the result using
+	// the main func's n variable
+	//
+	// so, that's why it prints the correct result here
+	fmt.Println("n is", n)
+}