feat: pointers, runes, structs

go-by-example/pointers/pointers.go

@@ -0,0 +1,26 @@
+package main
+
+import "fmt"
+
+// This functions creates a copy of the argument and does not change the original
+func zeroval(ival int) {
+	ival = 0
+}
+
+// Changes the value of the argument because it is a pointer.
+func zeroptr(iptr *int) {
+	*iptr = 0
+}
+
+func main() {
+	i := 1
+	fmt.Println("initial", i)
+
+	zeroval(i)
+	fmt.Println("zeroval", i)
+	// & operand means the address of the variable. Creates a pointer when a function needs that as argument
+	zeroptr(&i)
+	fmt.Println("zeroptr:", i)
+
+	fmt.Println("Poiner:", &i)
+}

go-by-example/strings-runes/strings-runes.go

@@ -0,0 +1,40 @@
+package main
+
+import (
+	"fmt"
+	"unicode/utf8"
+)
+
+func main() {
+	const s = "สวัสดี"
+	// Will output thte byte length and not the string length.
+	fmt.Println("Len:", len(s))
+
+	for i := range len(s) {
+		fmt.Printf("%x ", s[i])
+	}
+	fmt.Println()
+
+	fmt.Println("Rune Count: ", utf8.RuneCountInString(s))
+
+	for idx, runeValue := range s {
+		fmt.Printf("%#U starts at %d\n", runeValue, idx)
+	}
+
+	fmt.Println("\nUsing DecodeRuneInString")
+	for i, w := 0, 0; i < len(s); i += w {
+		runeValue, width := utf8.DecodeRuneInString(s[i:])
+		fmt.Printf("%#U starts at %d\n", runeValue, i)
+		w = width
+
+		examineRune(runeValue)
+	}
+}
+
+func examineRune(r rune) {
+	if r == 't' {
+		fmt.Println("found tee")
+	} else if r == 'ส' {
+		fmt.Println("found so sua")
+	}
+}

go-by-example/structs/structs.go

@@ -0,0 +1,42 @@
+package main
+
+import "fmt"
+
+type person struct {
+	name string
+	age  int
+}
+
+func newPerson(name string) *person {
+	p := person{name: name}
+	p.age = 42
+	return &p
+}
+
+func main() {
+	fmt.Println(person{"Bob", 20})
+	fmt.Println(person{"Alice", 30})
+	// fmt.Println(person{"Fred"}) // will zero value age. Compiler don't like it actually.
+	fmt.Println(&person{"Ann", 40})
+	fmt.Println(newPerson("Jon"))
+
+	s := person{name: "Sean", age: 50}
+
+	fmt.Println(s.name)
+
+	sp := &s
+	fmt.Println(sp.age)
+
+	sp.age = 51
+	fmt.Println(sp.age)
+
+	// If a single use struct you can omit the decalre the struct type and just use it directly on the initialization.
+	dog := struct {
+		name   string
+		isGood bool
+	}{
+		"Mike",
+		true,
+	}
+	fmt.Println(dog)
+}