The code and doc for lesson 1-3

code/ch1/hello/hello_world.go

@@ -0,0 +1,12 @@
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+func main() {
+	if len(os.Args) > 1 {
+		fmt.Println("Hello World", os.Args[1])
+	}
+}

code/ch2/constant_test/constant_try_test.go

@@ -0,0 +1,24 @@
+package constant_test
+
+import "testing"
+
+const (
+	Monday = 1 + iota
+	Tuesday
+	Wednesday
+)
+
+const (
+	Readable = 1 << iota
+	Writable
+	Executable
+)
+
+func TestConstantTry(t *testing.T) {
+	t.Log(Monday, Tuesday)
+}
+
+func TestConstantTry1(t *testing.T) {
+	a := 1 //0001
+	t.Log(a&Readable == Readable, a&Writable == Writable, a&Executable == Executable)
+}

code/ch2/fib/fib_test.go

@@ -0,0 +1,35 @@
+package fib
+
+import (
+	"testing"
+)
+
+func TestFibList(t *testing.T) {
+	// var a int = 1
+	// var b int = 1
+	// var (
+	// 	a int = 1
+	// 	b     = 1
+	// )
+	a := 1
+	// a := 1
+	b := 1
+	t.Log(a)
+	for i := 0; i < 5; i++ {
+		t.Log(" ", b)
+		tmp := a
+		a = b
+		b = tmp + a
+	}
+
+}
+
+func TestExchange(t *testing.T) {
+	a := 1
+	b := 2
+	// tmp := a
+	// a = b
+	// b = tmp
+	a, b = b, a
+	t.Log(a, b)
+}

code/ch3/type_test/type_test.go

@@ -0,0 +1,29 @@
+package type_test
+
+import "testing"
+
+type MyInt int64
+
+func TestImplicit(t *testing.T) {
+	var a int32 = 1
+	var b int64
+	b = int64(a)
+	var c MyInt
+	c = MyInt(b)
+	t.Log(a, b, c)
+}
+
+func TestPoint(t *testing.T) {
+	a := 1
+	aPtr := &a
+	//aPtr = aPtr + 1
+	t.Log(a, aPtr)
+	t.Logf("%T %T", a, aPtr)
+}
+
+func TestString(t *testing.T) {
+	var s string
+	t.Log("*" + s + "*") //初始化零值是“”
+	t.Log(len(s))
+
+}

code/ch4/operator_test/operator_test.go

@@ -0,0 +1,26 @@
+package operator_test
+
+import "testing"
+
+const (
+	Readable = 1 << iota
+	Writable
+	Executable
+)
+
+func TestCompareArray(t *testing.T) {
+	a := [...]int{1, 2, 3, 4}
+	b := [...]int{1, 3, 2, 4}
+	//	c := [...]int{1, 2, 3, 4, 5}
+	d := [...]int{1, 2, 3, 4}
+	t.Log(a == b)
+	//t.Log(a == c)
+	t.Log(a == d)
+}
+
+func TestBitClear(t *testing.T) {
+	a := 7 //0111
+	a = a &^ Readable
+	a = a &^ Executable
+	t.Log(a&Readable == Readable, a&Writable == Writable, a&Executable == Executable)
+}

code/ch5/condition/condition_test.go

@@ -0,0 +1,29 @@
+package condition_test
+
+import "testing"
+
+func TestSwitchMultiCase(t *testing.T) {
+	for i := 0; i < 5; i++ {
+		switch i {
+		case 0, 2:
+			t.Log("Even")
+		case 1, 3:
+			t.Log("Odd")
+		default:
+			t.Log("it is not 0-3")
+		}
+	}
+}
+
+func TestSwitchCaseCondition(t *testing.T) {
+	for i := 0; i < 5; i++ {
+		switch {
+		case i%2 == 0:
+			t.Log("Even")
+		case i%2 == 1:
+			t.Log("Odd")
+		default:
+			t.Log("unknow")
+		}
+	}
+}

code/ch5/loop/loop_test.go

@@ -0,0 +1,11 @@
+package loop_test
+
+import "testing"
+
+func TestWhileLoop(t *testing.T) {
+	n := 0
+	for n < 5 {
+		t.Log(n)
+		n++
+	}
+}

code/ch6/array_test/array_test.go

@@ -0,0 +1,28 @@
+package array_test
+
+import "testing"
+
+func TestArrayInit(t *testing.T) {
+	var arr [3]int
+	arr1 := [4]int{1, 2, 3, 4}
+	arr3 := [...]int{1, 3, 4, 5}
+	arr1[1] = 5
+	t.Log(arr[1], arr[2])
+	t.Log(arr1, arr3)
+}
+
+func TestArrayTravel(t *testing.T) {
+	arr3 := [...]int{1, 3, 4, 5}
+	for i := 0; i < len(arr3); i++ {
+		t.Log(arr3[i])
+	}
+	for _, e := range arr3 {
+		t.Log(e)
+	}
+}
+
+func TestArraySection(t *testing.T) {
+	arr3 := [...]int{1, 2, 3, 4, 5}
+	arr3_sec := arr3[:]
+	t.Log(arr3_sec)
+}

code/ch6/slice_test/slice_test.go

@@ -0,0 +1,49 @@
+package slice_test
+
+import "testing"
+
+func TestSliceInit(t *testing.T) {
+	var s0 []int
+	t.Log(len(s0), cap(s0))
+	s0 = append(s0, 1)
+	t.Log(len(s0), cap(s0))
+
+	s1 := []int{1, 2, 3, 4}
+	t.Log(len(s1), cap(s1))
+
+	s2 := make([]int, 3, 5)
+	t.Log(len(s2), cap(s2))
+	t.Log(s2[0], s2[1], s2[2])
+	s2 = append(s2, 1)
+	t.Log(s2[0], s2[1], s2[2], s2[3])
+	t.Log(len(s2), cap(s2))
+}
+
+func TestSliceGrowing(t *testing.T) {
+	s := []int{}
+	for i := 0; i < 10; i++ {
+		s = append(s, i)
+		t.Log(len(s), cap(s))
+	}
+}
+
+func TestSliceShareMemory(t *testing.T) {
+	year := []string{"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep",
+		"Oct", "Nov", "Dec"}
+	Q2 := year[3:6]
+	t.Log(Q2, len(Q2), cap(Q2))
+	summer := year[5:8]
+	t.Log(summer, len(summer), cap(summer))
+	summer[0] = "Unknow"
+	t.Log(Q2)
+	t.Log(year)
+}
+
+func TestSliceComparing(t *testing.T) {
+	a := []int{1, 2, 3, 4}
+	b := []int{1, 2, 3, 4}
+	// if a == b { //切片只能和nil比较
+	// 	t.Log("equal")
+	// }
+	t.Log(a, b)
+}