add section.4.3

ch4/section.4.3.go

@@ -0,0 +1,312 @@
+package main
+
+import (
+	"os"
+	"io"
+	"fmt"
+	"sort"
+	"bufio"
+	"unicode"
+	"unicode/utf8"
+)
+
+func main() {
+	var bTest bool
+	fmt.Println(bTest)
+
+	ages := make(map[string]int)
+	fmt.Println(ages)
+
+	ages2 := map[string]int{
+		"alice": 31,
+		"charlie": 34,
+	}
+	fmt.Println(ages2)
+
+	ages3 := make(map[string]int)
+	ages3["alice"] = 54
+	ages3["charlie"] = 33
+	fmt.Println(ages3)
+
+	ages3["alice"] = 22
+	fmt.Println(ages3["alice"])
+
+	delete(ages3, "alice")
+	fmt.Println(ages3)
+	ages3["bob"] = ages3["bob"] + 1
+	fmt.Println(ages3)
+	ages3["bob"] += 1
+	fmt.Println(ages3)
+	ages3["bob"]++
+	fmt.Println(ages3)
+	// fmt.Println(&ages3["bob"])  //cannot take address of ages3["bob"]
+
+	for name, age := range ages3 {
+		fmt.Printf("%s\t%d\n", name, age)
+	}
+
+	mapNum := map[int]int{}
+	for i := 	1; i <= 10; i++ {
+		mapNum[i]=i
+	}
+
+	//每次遍历顺序随机
+	for k, v := range mapNum {
+		fmt.Printf("%d\t%d\n", k, v)
+	}
+
+	var nums []int
+	for num := range mapNum {
+		nums = append(nums, num)
+	}
+
+	sort.Ints(nums)
+	for _, num := range nums {
+		fmt.Printf("%d\t%d\n", num, mapNum[num])
+	}
+
+	ages4 := map[string]int{
+		"alice": 31,
+		"charlie": 34,
+		"peter": 31,
+		"jason": 34,
+		"Lily": 31,
+		"Lucy": 34,
+	}
+
+	// var names []string
+	names := make([]string, 0, len(ages4))
+
+	for name := range ages4 {
+	names = append(names, name)
+	} 
+	sort.Strings(names)
+	for _, name := range names {
+		fmt.Printf("%s\t%d\n", name, ages4[name])
+	}
+
+	var ages5 map[string]int
+	fmt.Println(ages5 == nil)
+	fmt.Println(len(ages5) == 0)
+	// ages5["a"] = 1    //panic: assignment to entry in nil map
+	ages6 := make(map[string]int, 10)
+	fmt.Println(ages6 == nil)
+	fmt.Println(len(ages6) == 0)
+	ages6["a"] = 1
+
+	ages7 := map[string]int{
+		"alice": 31,
+		"charlie": 34,
+		"peter": 31,
+		"jason": 34,
+		"Lily": 31,
+		"Lucy": 34,
+	}
+
+	age, ok := ages7["bob"]
+	if !ok {
+		fmt.Println("bob is not in map", age)
+	}
+
+	if _, ok := ages["bob"]; !ok { /* ... */ }
+
+	fmt.Println(equal(ages7, ages7))
+	fmt.Println(equal(ages6, ages7))
+
+	// dedup()
+	var list []byte
+	for i := byte(0); i < 128; i++ {
+		list = append(list, i)
+	}
+	fmt.Println(k2(list))
+
+	fmt.Println("\x00\x01")
+	fmt.Println("\a")
+	fmt.Printf("%s", "aaaaa\v")
+	fmt.Printf("%s", "aaaaa\f")
+	fmt.Printf("%s", "aaaaa\r")
+
+	testASCII();
+
+	var str = []string{"abcccccdef", "abcdddddd", "aaaabbbb"}
+	fmt.Println(str)
+	fmt.Println(k(str))
+
+	var str2 = []string{"a", "b", "c"}
+	var str3 = []string{"a", "b", "c"}
+	var str4 = []string{"a", "c", "c"}
+	Add(str)
+	Add(str2)
+	Add(str3)
+	Add(str4)
+	fmt.Println(Count(str), Count(str2), Count(str3), Count(str4))
+
+	// charCount()
+
+	graph := make(map[string]map[string]bool)
+	fmt.Printf("graph type is:%T\n", graph)
+
+	charCount2()
+}
+
+func equal(x, y map[string]int) bool {
+	if len(x) != len(y) {
+		return false
+	}
+
+	for k, v := range x {
+		if _, ok := y[k]; !ok {
+			return false
+		}else {
+			if v != y[k] {
+				return  false
+			}
+		}
+	}
+
+	return true
+}
+
+func dedup() {
+	seen := make(map[string]bool) // a set of strings
+	input := bufio.NewScanner(os.Stdin)
+	for input.Scan() {
+		line := input.Text()
+		if !seen[line] {
+		seen[line] = true
+		fmt.Println(line)
+		}
+	}
+
+	if err := input.Err(); err != nil {
+		fmt.Fprintf(os.Stderr, "dedup: %v\n", err)
+		os.Exit(1)
+	}
+}
+
+func testASCII() {
+	f, err := os.OpenFile("./test.txt", os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0666)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "dup2: %v\n", err)
+		os.Exit(1)
+	}
+	defer f.Close()
+
+	output := bufio.NewWriter(f)
+	output.WriteString("aaaaa\v")
+	output.WriteString("aaaaa\f")
+	output.WriteString("aaaaa")
+	err = output.Flush()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "output.Flush: %v\n", err)
+		os.Exit(1)
+	}
+}
+
+var m = make(map[string]int)
+
+func k(list []string) string {return fmt.Sprintf("%q", list)}
+func Add(list []string) {m[k(list)]++}
+func Count(list []string) int {return m[k(list)]}
+
+func k2(list []byte) string {return fmt.Sprintf("%q", list)}
+
+func charCount() {
+	counts := make(map[rune]int) // counts of Unicode characters
+	var utflen [utf8.UTFMax + 1]int // count of lengths of UTF-8 encodings
+	invalid := 0 // count of invalid UTF-8 characters
+	in := bufio.NewReader(os.Stdin)
+	for {
+		r, n, err := in.ReadRune() // returns rune, nbytes, error
+		if err == io.EOF {
+			break
+		}
+
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "charcount: %v\n", err)
+			os.Exit(1)
+		}
+
+		if r == unicode.ReplacementChar && n == 1 {
+			invalid++
+			continue
+		}
+		counts[r]++
+		utflen[n]++
+	}
+	fmt.Printf("rune\tcount\n")
+
+	for c, n := range counts {
+		fmt.Printf("%q\t%d\n", c, n)
+	}
+	fmt.Print("\nlen\tcount\n")
+
+	for i, n := range utflen {
+		if i > 0 {
+			fmt.Printf("%d\t%d\n", i, n)
+		}
+	}
+
+	if invalid > 0 {
+		fmt.Printf("\n%d invalid UTF-8 characters\n", invalid)
+	}
+}
+
+const (
+	LETTER = iota + 1
+	DIGITAL
+	COUNT_MAX
+)
+
+func charCount2() {
+	counts := make(map[rune]int) // counts of Unicode characters
+	var utflen [utf8.UTFMax + 1]int // count of lengths of UTF-8 encodings
+	invalid := 0 // count of invalid UTF-8 characters
+	var letters, digits int
+	in := bufio.NewReader(os.Stdin)
+	for {
+		r, n, err := in.ReadRune() // returns rune, nbytes, error
+		if err == io.EOF {
+			break
+		}
+
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "charcount: %v\n", err)
+			os.Exit(1)
+		}
+
+		if r == unicode.ReplacementChar && n == 1 {
+			invalid++
+			continue
+		}
+		counts[r]++
+		utflen[n]++
+
+		if unicode.IsLetter(r) {
+			letters++
+		}
+
+		if unicode.IsNumber(r) {
+			digits++
+		}
+	}
+	fmt.Printf("letters\tcount:%d\n", letters)
+	fmt.Printf("digits\tcount:%d\n", digits)
+
+	fmt.Printf("rune\tcount\n")
+
+	for c, n := range counts {
+		fmt.Printf("%q\t%d\n", c, n)
+	}
+	fmt.Print("\nlen\tcount\n")
+
+	for i, n := range utflen {
+		if i > 0 {
+			fmt.Printf("%d\t%d\n", i, n)
+		}
+	}
+
+	if invalid > 0 {
+		fmt.Printf("\n%d invalid UTF-8 characters\n", invalid)
+	}
+}