code demos for CH9,CH10

code/ch10/func/func_test.go

@@ -0,0 +1,56 @@
+package fn_test
+
+import (
+	"fmt"
+	"math/rand"
+	"testing"
+	"time"
+)
+
+func returnMultiValues() (int, int) {
+	return rand.Intn(10), rand.Intn(20)
+}
+
+func timeSpent(inner func(op int) int) func(op int) int {
+	return func(n int) int {
+		start := time.Now()
+		ret := inner(n)
+		fmt.Println("time spent:", time.Since(start).Seconds())
+		return ret
+	}
+}
+
+func slowFun(op int) int {
+	time.Sleep(time.Second * 1)
+	return op
+}
+
+func TestFn(t *testing.T) {
+	a, _ := returnMultiValues()
+	t.Log(a)
+	tsSF := timeSpent(slowFun)
+	t.Log(tsSF(10))
+}
+
+func Sum(ops ...int) int {
+	ret := 0
+	for _, op := range ops {
+		ret += op
+	}
+	return ret
+}
+
+func TestVarParam(t *testing.T) {
+	t.Log(Sum(1, 2, 3, 4))
+	t.Log(Sum(1, 2, 3, 4, 5))
+}
+
+func Clear() {
+	fmt.Println("Clear resources.")
+}
+
+func TestDefer(t *testing.T) {
+	defer Clear()
+	fmt.Println("Start")
+	panic("err")
+}

code/ch9/string/string_fun_test.go

@@ -0,0 +1,24 @@
+package string_test
+
+import (
+	"strconv"
+	"strings"
+	"testing"
+)
+
+func TestStringFn(t *testing.T) {
+	s := "A,B,C"
+	parts := strings.Split(s, ",")
+	for _, part := range parts {
+		t.Log(part)
+	}
+	t.Log(strings.Join(parts, "-"))
+}
+
+func TestConv(t *testing.T) {
+	s := strconv.Itoa(10)
+	t.Log("str" + s)
+	if i, err := strconv.Atoi("10"); err == nil {
+		t.Log(10 + i)
+	}
+}

code/ch9/string/string_test.go

@@ -0,0 +1,32 @@
+package string_test
+
+import (
+	"testing"
+)
+
+func TestString(t *testing.T) {
+	var s string
+	t.Log(s) //初始化为默认零值“”
+	s = "hello"
+	t.Log(len(s))
+	//s[1] = '3' //string是不可变的byte slice
+	//s = "\xE4\xB8\xA5" //可以存储任何二进制数据
+	s = "\xE4\xBA\xBB\xFF"
+	t.Log(s)
+	t.Log(len(s))
+	s = "中"
+	t.Log(len(s)) //是byte数
+
+	c := []rune(s)
+	t.Log(len(c))
+	//	t.Log("rune size:", unsafe.Sizeof(c[0]))
+	t.Logf("中 unicode %x", c[0])
+	t.Logf("中 UTF8 %x", s)
+}
+
+func TestStringToRune(t *testing.T) {
+	s := "中华人民共和国"
+	for _, c := range s {
+		t.Logf("%[1]c %[1]x", c)
+	}
+}