add: slices - first part

x-tba/strings-revisited/03-string-indexing-slicing/main.go

@@ -0,0 +1,57 @@
+// 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() {
+	// GOALS:
+	// 1- String value is immutable
+	// 2- Indexing vs Slicing
+	// 3- Using bytes for manipulating strings
+
+	mood := "wonder"
+
+	// 1- a string value is immutable (read-only)
+	// mood[1] = 'a'
+
+	// 2- Indexing vs Slicing
+
+	// "wonder"
+	//  ^ ^^^^
+	//  | ||||
+	// "wandering"
+
+	//              "w"     + "a" + "nder"   + "ing"
+
+	// wandering := mood[0] + "a" + mood[2:] + "ing"
+	// fmt.Printf("mood[0]   : %T - %[1]v\n", mood[0])   // byte
+	// fmt.Printf("mood[0:1] : %T - %[1]v\n", mood[0:1]) // string
+
+	// wandering := mood[:1] + "a" + mood[2:] + "ing"
+	fmt.Println(mood)
+	// fmt.Println(wandering)
+
+	// 3- converting creates a new byte slice (allocation)
+	b := []byte(mood)
+	b[1] = 'a'
+
+	// b = append(b, 'i', 'n', 'g')
+	// b = append(b, []byte{'i', 'n', 'g'})
+	b = append(b, "ing"...)
+
+	// starts copying from the first element
+	copy(b, "listen")
+
+	// starts copying from the "7th" element
+	copy(b[6:], "ed.")
+
+	fmt.Println(string(b))
+}