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15-slices/01-intro/01-theory/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() {
+	// -----------------------------------------------------
+	// COMPLEX LITERALS:
+	// -----------------------------------------------------
+	// array literal : [4]int{1, 2, 3}
+	// slice literal : []int{1, 2, 3}
+	//
+	// You didn't learn about these yet:
+	//
+	// map literal   : map[int]int{1: 2}
+	// struct literal: struct{ x, y int }{ 1, 2 }
+
+	// -----------------------------------------------------
+	// SLICE LITERAL:
+	// -----------------------------------------------------
+	r := []rune{'h', 'e', 'y'} // 3 items
+	i := []int{'h', 'e', 'y'}  // 3 items
+	b := []byte{'h', 'e', 'y'} // 3 items
+	s := []string{"hey"}       // 1 item
+
+	fmt.Printf("[]rune  type: %T\n", r)
+	fmt.Printf("[]int   type: %T\n", i)
+	fmt.Printf("[]byte  type: %T\n", b)
+	fmt.Printf("[]string type: %T\n", s)
+
+	// -----------------------------------------------------
+	// multi-dimensional slice
+	// -----------------------------------------------------
+	multi := [][]rune{
+		{1, 2, 3},
+		// each item can have a different length
+		{4, 5, 6, 7, 8},
+	}
+	fmt.Printf("multi's type     : %T\n", multi)
+	fmt.Printf("multi's length   : %d\n", len(multi))
+	fmt.Printf("multi[0]'s length: %d\n", len(multi[0]))
+	fmt.Printf("multi[1]'s length: %d\n", len(multi[1]))
+
+	// -----------------------------------------------------
+	// getting and setting elements
+	// -----------------------------------------------------
+	hello := []rune{'h', 'e', 'y'}
+	fmt.Println(hello[0], hello[1], hello[2])
+
+	hello[0] = 'y'
+	hello[1] = 'o'
+	hello[2] = '!'
+	fmt.Println(hello[0], hello[1], hello[2])
+
+	// -----------------------------------------------------
+	// empty slice
+	// -----------------------------------------------------
+	e := []rune{}
+	fmt.Printf("empty slice's length: %d\n", len(e))
+
+	// -----------------------------------------------------
+	// nil slice
+	// slice's zero value is nil
+	// -----------------------------------------------------
+	var n []rune
+	fmt.Println("Really nil?", n == nil)
+
+	// you can't get/set elements of a nil slice
+	// if you run the code below, it will error at runtime
+	//
+	// fmt.Println(n[0])
+	// fmt.Println(n[1])
+
+	// but you can get its length
+	fmt.Printf("nil slice's length: %d\n", len(n))
+}