Initial commit

10-constants/01-declarations/01-syntax/04-rules/01-immutability/main.go

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+// 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
+
+func main() {
+	const max int = 100
+
+	// ERROR: cannot assign to max
+	//        constants are immutable (cannot change)
+	// max = 100
+}

10-constants/01-declarations/01-syntax/04-rules/02-runtime-func/main.go

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+// 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"
+	"math"
+)
+
+func main() {
+	// math.Pow calculates the power of the given number
+	fmt.Println(math.Pow10(2)) // 100
+	fmt.Println(math.Pow10(3)) // 1000
+	fmt.Println(math.Pow10(4)) // 10000
+
+	// ERROR: math.Pow is not a constant
+	//        constants cannot use runtime constructs
+
+	// const max int = math.Pow10(2)
+}

10-constants/01-declarations/01-syntax/04-rules/03-runtime-var/main.go

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+// 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
+
+func main() {
+	n := 2
+
+	// ERROR: n is not a constant
+	// const max int = n
+
+	_ = n
+}

10-constants/01-declarations/01-syntax/04-rules/04-len/main.go

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+// 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"
+
+func main() {
+	// When argument to len is a constant, len can be used
+	// while initializing a constant
+	//
+	// Here, "Hello" is a constant.
+
+	const max int = len("Hello")
+
+	fmt.Println(max)
+}