first commit

Author: dgunjetti

.vscode/launch.json

@@ -0,0 +1,24 @@
+{
+  // Use IntelliSense to learn about possible attributes.
+  // Hover to view descriptions of existing attributes.
+  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "name": "Launch file",
+      "type": "go",
+      "request": "launch",
+      "mode": "debug",
+      "program": "${file}"
+    },
+    {
+      "name": "Launch",
+      "type": "go",
+      "request": "launch",
+      "mode": "auto",
+      "program": "${fileDirname}",
+      "env": {},
+      "args": []
+    }
+  ]
+}

01-Hello/hello/hello.go

@@ -0,0 +1,7 @@
+package main
+
+import "fmt"
+
+func main() {
+	fmt.Printf("hello world\n")
+}

01-Hello/hello2/hello.go

@@ -0,0 +1,11 @@
+package main
+
+import (
+	"fmt"
+
+	"gosrc/01-Hello/stringutil"
+)
+
+func main() {
+	fmt.Println(stringutil.Reverse("hello world"))
+}

01-Hello/stringutil/reverse.go

@@ -0,0 +1,10 @@
+package stringutil
+
+//Reverse the input string
+func Reverse(s string) string {
+	r := []rune(s)
+	for i, j := 0, len(r)-1; i < len(r)/2; i, j = i+1, j-1 {
+		r[i], r[j] = r[j], r[i]
+	}
+	return string(r)
+}

01-Hello/stringutil/reverse_test.go

@@ -0,0 +1,19 @@
+package stringutil
+
+import "testing"
+
+func TestReverse(t *testing.T) {
+	cases := []struct {
+		in, want string
+	}{
+		{"Hello, world", "dlrow ,olleH"},
+		{"", ""},
+	}
+
+	for _, c := range cases {
+		got := Reverse(c.in)
+		if got != c.want {
+			t.Errorf("Reverse(%q) == %q, want %q", c.in, got, c.want)
+		}
+	}
+}

02-ProgramStructure/01-var/main.go

@@ -0,0 +1,20 @@
+package main
+
+import "fmt"
+
+func main() {
+	var s string
+	var s1 string = "hello"
+	var s2 = "world"
+
+	var i, j, k int
+	var b, f, s3 = true, 2.3, "hello"
+
+	fmt.Printf("s=%s, s1=%s s2=%s\n", s, s1, s2)
+	fmt.Printf("i=%d, j=%d, k=%d\n", i, j, k)
+	fmt.Printf("b=%t, f=%f, s3=%s\n", b, f, s3)
+
+	m := 10
+	fmt.Printf("m=%d\n", m)
+
+}

02-ProgramStructure/02-pointer/main.go

@@ -0,0 +1,12 @@
+package main
+
+import "fmt"
+
+func main() {
+	x := 100
+	p := &x
+	fmt.Println(*p)
+
+	*p = 2
+	fmt.Println(x)
+}

02-ProgramStructure/03-pointer-compare/main.go

@@ -0,0 +1,10 @@
+package main
+
+import "fmt"
+
+func main() {
+	x := 100
+	y := 200
+
+	fmt.Println(&x == &x, &x == &y, &x == nil)
+}

02-ProgramStructure/04-pointer-arg/main.go

@@ -0,0 +1,12 @@
+package main
+
+import "fmt"
+
+func incr(p *int) {
+	*p++
+}
+func main() {
+	x := 100
+	incr(&x)
+	fmt.Println(x)
+}

02-ProgramStructure/04-pointer-return/main.go

@@ -0,0 +1,13 @@
+package main
+
+import "fmt"
+
+func f() *int {
+	v := 100
+	return &v
+}
+
+func main() {
+	var p = f()
+	fmt.Println(*p)
+}

02-ProgramStructure/05-new/main.go

@@ -0,0 +1,9 @@
+package main
+
+import "fmt"
+
+func main() {
+	p := new(int)
+	*p = 2
+	fmt.Println(*p)
+}

02-ProgramStructure/06-lifetime/main.go

@@ -0,0 +1,21 @@
+package main
+
+var global *int
+
+func f() {
+	// heap allocated
+	var x int
+	x = 100
+	global = &x
+}
+
+func g() {
+	// stack allocated
+	y := new(int)
+	*y = 1
+}
+
+func main() {
+	f()
+	g()
+}

02-ProgramStructure/07-namedtypes/main.go

@@ -0,0 +1,13 @@
+package main
+
+import "fmt"
+
+type celcius float64
+type fahreneit float64
+
+func main() {
+	var c celcius
+	var f fahreneit
+
+	fmt.Println(c == f)
+}

02-ProgramStructure/08-method/main.go

@@ -0,0 +1,16 @@
+package main
+
+import "fmt"
+
+// Celcius type declaration
+type Celcius float64
+
+func (c Celcius) String() string {
+	return fmt.Sprintf("%gC", c)
+}
+
+func main() {
+	var c Celcius
+	c = 100
+	fmt.Println(c)
+}

02-ProgramStructure/scope/main.go

@@ -0,0 +1,24 @@
+package main
+
+import "fmt"
+
+func f() int {
+	return 100
+}
+
+func g() int {
+	return 200
+}
+
+func main() {
+	if x := f(); x == 0 {
+		fmt.Println(x)
+	} else if y := g(); x == y {
+		fmt.Println(x, y)
+	} else {
+		fmt.Println(x, y)
+	}
+
+	// declaration error
+	fmt.Println(x, y)
+}

02-ProgramStructure/scope2/abc

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+func main() {
+	f, err := os.Open("abc")
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+	fmt.Println(f.Stat())
+}

02-ProgramStructure/scope2/main.go

@@ -0,0 +1,9 @@
+package main
+
+import "fmt"
+
+func main() {
+	for x := 0; x < 10; x++ {
+		fmt.Println(x)
+	}
+}

03-Constructs/01-for/main.go

@@ -0,0 +1,11 @@
+package main
+
+import "fmt"
+
+func main() {
+	x := 1
+	for x < 10 {
+		x++
+	}
+	fmt.Println(x)
+}

03-Constructs/01-for2/main.go

@@ -0,0 +1,11 @@
+package main
+
+func main() {
+	x := 1
+	for {
+		x++
+		if x < 10 {
+			break
+		}
+	}
+}

03-Constructs/01-for3/main.go

@@ -0,0 +1,13 @@
+package main
+
+import "fmt"
+
+func main() {
+	for i, v := range []string{"simon", "jessy"} {
+		fmt.Println(i, v)
+	}
+
+	for _, v := range []string{"peter", "mark"} {
+		fmt.Println(v)
+	}
+}

03-Constructs/01-for4/main.go

@@ -0,0 +1,10 @@
+package main
+
+func main() {
+	a := 15
+	for i := 1; i < 20; i++ {
+		if i == a {
+			break
+		}
+	}
+}

03-Constructs/02-break/main.go

@@ -0,0 +1,17 @@
+package main
+
+import "fmt"
+
+func main() {
+	a := 0
+Loop:
+	for i := 0; i < 20; i++ {
+		for j := 0; j < 10; i++ {
+			if a == 15 {
+				break Loop
+			}
+			a++
+		}
+	}
+	fmt.Println(a)
+}

03-Constructs/02-break2/main.go

@@ -0,0 +1,12 @@
+package main
+
+import "fmt"
+
+func main() {
+	for i := 0; i < 10; i++ {
+		if i%2 == 0 {
+			continue
+		}
+		fmt.Println(i)
+	}
+}

03-Constructs/02-continue/main.go

@@ -0,0 +1,25 @@
+package main
+
+import "fmt"
+
+func coinflip(x int) string {
+	if x%2 == 0 {
+		return "heads"
+	} else {
+		return "tails"
+	}
+}
+
+func main() {
+	var heads, tails int
+	for i := 0; i < 10; i++ {
+		switch coinflip(i) {
+		case "heads":
+			heads++
+		case "tails":
+			tails++
+		default:
+		}
+	}
+	fmt.Println(heads, tails)
+}

03-Constructs/03-switch/main.go

@@ -0,0 +1,10 @@
+package main
+
+func main() {
+	x := 100
+	switch {
+	case x > 0:
+	case x < 0:
+	default:
+	}
+}

03-Constructs/03-switch2/main.go

@@ -0,0 +1,13 @@
+package main
+
+func f() int {
+	return 100
+}
+func main() {
+	switch x := f(); x {
+	case 100:
+		x = x + 50
+	case 200:
+	default:
+	}
+}