feat: init & playaround

go-by-example/arrays/arrays.go

@@ -0,0 +1,38 @@
+package main
+
+import "fmt"
+
+func main() {
+
+	var a [5]int
+	fmt.Println("emp:", a)
+
+	a[4] = 100
+	fmt.Println("set:", a)
+	fmt.Println("get:", a[4])
+
+	fmt.Println("len:", len(a))
+
+	b := [5]int{1, 2, 3, 4, 5}
+	fmt.Println("dcl:", b)
+	// Compiler counts for you.
+	b = [...]int{1, 2, 3, 4, 5}
+	fmt.Println("dcl:", b)
+
+	b = [...]int{100, 3: 400, 500}
+	fmt.Println("idx:", b)
+
+	var twoD [2][3]int
+	for i := range 2 {
+		for j := range 3 {
+			twoD[i][j] = i + j
+		}
+	}
+	fmt.Println("2d: ", twoD)
+
+	twoD = [2][3]int{
+		{1, 2, 3},
+		{1, 2, 3},
+	}
+	fmt.Println("2d: ", twoD)
+}

go-by-example/constants/constants.go

@@ -0,0 +1,22 @@
+package main
+
+import (
+	"fmt"
+	"math"
+)
+
+const s string = "constant"
+
+func main() {
+	fmt.Println(s)
+
+	const n = 500000000
+
+	const d = 3e20 / n
+
+	fmt.Println(d)
+
+	fmt.Println(int64(d))
+
+	fmt.Println(math.Sin(n))
+}

go-by-example/for/for.go

@@ -0,0 +1,35 @@
+package main
+
+import "fmt"
+
+func main() {
+
+	// Basic
+	i := 1
+	for i <= 3 {
+		fmt.Println(i)
+		i = i + 1
+	}
+
+	// Classic initial/conditional/after loop
+	for j := 0; j < 3; j++ {
+		fmt.Println(j)
+	}
+	// or modernized
+	for j := range 3 {
+		fmt.Println("range", j)
+	}
+	// Will run until break
+	for {
+		fmt.Println("Break")
+		break
+	}
+	// Continue
+	for n := range 10 {
+		if n%2 == 0 {
+			continue
+		}
+		fmt.Println(n)
+	}
+
+}

go-by-example/functions/functions.go

@@ -0,0 +1,33 @@
+package main
+
+import "fmt"
+
+func plus(a int, b int) int {
+	return a + b
+}
+
+func plusPlus(a, b, c int) int {
+	return a + b + c
+}
+
+func vals() (int, int) {
+	return 3, 7
+}
+
+func main() {
+
+	res := plus(1, 2)
+	fmt.Println("1 + 2 =", res)
+
+	res = plusPlus(1, 2, 3)
+	fmt.Println("1 + 2 + 3 =", res)
+
+	a, b := vals()
+
+	fmt.Println(a)
+	fmt.Println(b)
+
+	_, c := vals()
+	fmt.Println(c)
+
+}

go-by-example/hello-world/hello-world.go

@@ -0,0 +1,7 @@
+package main
+
+import "fmt"
+
+func main() {
+	fmt.Println("Hello, World!")
+}

go-by-example/maps/maps.go

@@ -0,0 +1,42 @@
+package main
+
+import (
+	"fmt"
+	"maps"
+)
+
+func main() {
+
+	m := make(map[string]int)
+
+	m["k1"] = 7
+	m["k2"] = 13
+
+	fmt.Println("map:", m)
+
+	v1 := m["k1"]
+	fmt.Println("v1", v1)
+
+	v3 := m["k3"]
+	fmt.Println("v3:", v3)
+
+	fmt.Println("len:", len(m))
+
+	delete(m, "k2")
+	fmt.Println("map:", m)
+
+	clear(m)
+	fmt.Println("map:", m)
+
+	_, prs := m["k2"]
+	fmt.Println("prs:", prs)
+
+	n := map[string]int{"foo": 1, "bar": 2}
+	fmt.Println("map:", n)
+
+	n2 := map[string]int{"foo": 1, "bar": 2}
+
+	if maps.Equal(n, n2) {
+		fmt.Println("n == n2")
+	}
+}

go-by-example/slices/slices.go

@@ -0,0 +1,48 @@
+package main
+
+import (
+	"fmt"
+	// "slices"
+)
+
+func main() {
+
+	var s []string
+	fmt.Println("uninit", s, s == nil, len(s) == 0)
+
+	s = make([]string, 3)
+	fmt.Println("emp:", s, "len:", len(s), "cap:", cap(s))
+
+	s[0] = "a"
+	s[1] = "b"
+	s[2] = "c"
+
+	fmt.Println("set:", s)
+	fmt.Println("get:", s[2])
+
+	s = append(s, "d")
+	s = append(s, "e", "f")
+
+	fmt.Println("apd:", s)
+
+	f := make([]int, 3, 10)
+	fmt.Println("f:", f, "len:", len(f), "cap:", cap(f))
+
+	c := make([]string, len(s))
+	copy(c, s)
+	fmt.Println("cpy:", c)
+
+	l := s[2:5]
+	fmt.Println("sl1:", l)
+	// two d slices
+	twoD := make([][]int, 10)
+
+	for i := range len(twoD) {
+		innerLen := i + 1
+		twoD[i] = make([]int, innerLen)
+		for j := range innerLen {
+			twoD[i][j] = 1 + j
+		}
+	}
+	fmt.Println("2d: ", twoD)
+}

go-by-example/switch/switch.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+func main() {
+
+	i := 2
+	fmt.Print("Write ", i, " as ")
+	switch i {
+	case 1:
+		fmt.Println("one")
+	case 2:
+		fmt.Println("two")
+	case 3:
+		fmt.Println("three")
+	}
+
+	switch time.Now().Weekday() {
+	case time.Saturday, time.Sunday:
+		fmt.Println("It's the weekend")
+	default:
+		fmt.Println("It's a weekday")
+	}
+
+	t := time.Now()
+	switch {
+	case t.Hour() < 12:
+		fmt.Println("It's before noon")
+	default:
+		fmt.Println("It's after noon")
+	}
+
+	whatAmI := func(i interface{}) {
+		switch t := i.(type) {
+		case bool:
+			fmt.Println("I'm a bool")
+		case int:
+			fmt.Println("I'm an int")
+		default:
+			fmt.Printf("Don't know type %T\n", t)
+		}
+	}
+	whatAmI(true)
+	whatAmI(1)
+	whatAmI("hey")
+}

go-by-example/values/values.go

@@ -0,0 +1,17 @@
+package main
+
+import "fmt"
+
+func main() {
+
+	fmt.Println("go" + "lang")
+
+	fmt.Println("1+1 =", 1+1)
+
+	fmt.Println("7.0/3.0 =", 7.0/3.0)
+
+	fmt.Println(true && false)
+	fmt.Println(true || false)
+	fmt.Println(!true)
+
+}

go-by-example/variables/variables.go

@@ -0,0 +1,22 @@
+package main
+
+import "fmt"
+
+func main() {
+
+	var a = "initial"
+	fmt.Println(a)
+
+	var b, c int = 1, 2
+	fmt.Println(b, c)
+
+	var d = true
+	fmt.Println(d)
+
+	var e int
+	fmt.Println(e)
+
+	f := "apple"
+	fmt.Println(f)
+
+}