22 - 信道

Signed-off-by: Tinywan <756684177@qq.com>

Author: Tinywan

README.md

@@ -56,7 +56,7 @@ $ go get github.com/Tinywan/golang-tutorial
 
 ###  20 - 并发介绍  
 ###  [ 21 - 协程](/docs/golang_tutorial_21.md)  
-###  22 - 管道  
+###  [22 - 信道](/docs/golang_tutorial_22.md)  
 ###  23 - 缓冲信道和工作池  
 ###  24 - Select   
 ###  25 - Mutex  

demo/channel/deadlock.go

@@ -0,0 +1,6 @@
+package main
+
+func main() {
+	m := make(chan int)
+	m <- 5
+}

demo/channel/demo01.go

@@ -5,17 +5,14 @@ import (
 )
 
 func main() {
-	var m map[string]string
-	if m == nil {
-		fmt.Println("this is nil map")
+	var c chan int // 信道 c 的值为 nil
+	if c == nil {
+		fmt.Println("channel a is nil, going to define it")
+		c = make(chan int)
+		fmt.Printf("Type of c is %T", c) // 打印通道类型
 	}
-	m = make(map[string]string)
-	m["name"] = "Tinywan"
-	fmt.Println(m)
 
-	m1 := map[string]int{}
-	fmt.Println(m1)
-	m1["age"] = 24
-	m1["dateTime"] = 20180909
-	fmt.Println(m1)
+	fmt.Printf("\n")
+	a := make(chan int)
+	fmt.Printf("%T", a) // chan int
 }

demo/channel/goroutines.go

@@ -0,0 +1,27 @@
+package main
+
+import (
+	"fmt"
+)
+
+func hello(done chan bool) {
+	fmt.Println("This is hello goroutines")
+	done <- true
+}
+
+func getName(name chan string) {
+	fmt.Println("This is getName goroutines")
+	name <- "Tinywan"
+}
+
+func main() {
+	done := make(chan bool)
+	go hello(done)
+	<-done
+
+	name := make(chan string)
+	go getName(name)
+	fmt.Println(<-name)
+
+	fmt.Println("This is main function")
+}

demo/channel/range.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"fmt"
+)
+
+func producer(num chan int) {
+	for i := 0; i < 10; i++ {
+		num <- i
+	}
+	close(num)
+}
+
+func main() {
+	ch := make(chan int)
+	go producer(ch)
+
+	// for {
+	// 	v, ok := <-ch
+	// 	if ok == false { // 如果 ok 是 false 表示信道已经被关闭
+	// 		break // 通过 break 退出循环
+	// 	}
+	// 	fmt.Println("Received", v, ok)
+	// }
+
+	for v := range ch {
+		fmt.Println("Received ", v)
+	}
+}

demo/channel/single_chan.go

@@ -0,0 +1,18 @@
+package main
+
+import ()
+import "fmt"
+
+func sendData(d chan<- int) {
+	d <- 5
+}
+
+func main() {
+	d := make(chan<- int)
+	go sendData(d)
+	//fmt.Println(<-d) //试图从一个只写信道中接收数据
+
+	m := make(chan int) // 将双向信道转换为只写或只读信道
+	go sendData(m)
+	fmt.Println(<-m)
+}

demo/channel/sleep_goroutines.go

@@ -0,0 +1,21 @@
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+func hello(done chan bool) {
+	fmt.Println("hello go routine is going to sleep")
+	time.Sleep(4 * time.Second)
+	fmt.Println("hello go routine awake and going to write to done")
+	done <- true
+}
+
+func main() {
+	done := make(chan bool)
+	fmt.Println("Main going to call hello go goroutine")
+	go hello(done)
+	<-done
+	fmt.Println("Main received data")
+}

demo/channel/squares.go

@@ -0,0 +1,36 @@
+package main
+
+import (
+	"fmt"
+)
+
+// 计算 number 每一位的平方和
+func calcSquares(number int, squareop chan int) {
+	sum := 0
+	for number != 0 {
+		digit := number % 10
+		sum += digit * digit
+		number /= 10
+	}
+	squareop <- sum // 将结果发送给信道 squareop
+}
+
+func calcCubes(number int, cubeop chan int) {
+	sum := 0
+	for number != 0 {
+		digit := number % 10
+		sum += digit * digit * digit
+		number /= 10
+	}
+	cubeop <- sum
+}
+
+func main() {
+	number := 598
+	squareop := make(chan int)
+	cubeop := make(chan int)
+	go calcSquares(number, squareop)
+	go calcCubes(number, cubeop)
+	squares, cubes := <-squareop, <-cubeop
+	fmt.Println("Final output", squares+cubes)
+}

demo/string/demo01.go

@@ -0,0 +1,40 @@
+package main
+
+import (
+	"fmt"
+)
+
+// 打印字符串中的字节
+func printBytes(s string) {
+	for i := 0; i < len(s); i++ {
+		fmt.Printf("%x ", s[i])
+	}
+}
+
+// 打印字符串中的字符
+func printChars(s string) {
+	for i := 0; i < len(s); i++ {
+		fmt.Printf("%c", s[i])
+	}
+}
+
+func main() {
+	name := "Hello World"
+	printBytes(name)
+	fmt.Printf("\n")
+	printChars(name)
+
+	fmt.Printf("\n")
+	// d
+	name = "Señor"
+	printBytes(name)
+	fmt.Printf("\n")
+	printChars(name)
+
+	fmt.Printf("\n")
+	name = "萬少波"
+	printBytes(name)
+	fmt.Printf("\n")
+	printChars(name)
+
+}

demo/string/range.go

@@ -0,0 +1,16 @@
+package main
+
+import (
+	"fmt"
+)
+
+func printCharsAndBytes(s string) {
+	for index, rune := range s {
+		fmt.Printf("%c starts at byte %d\n", rune, index)
+	}
+}
+
+func main() {
+	name := "Señor"
+	printCharsAndBytes(name)
+}