Go Language Advanced

aggregate , passageway , section , Error handling , Interface

package mainimport (    "fmt"    "time")//8 Member variables var i intvar s bool = falsefunc main() {    //1 variable Statement     //go Medium String s To be lowercase, it has no concept of class     var s string = " Lin daiyu "    var a int = 1    var b int = 1    fmt.Println(a + b)    fmt.Println("hello world!")    fmt.Println(s)    var c, d int = 1, 2    fmt.Println(c + d)    //2  Variable declarations     const e, f = " Xue Baochai ", " Jia Baoyu "    fmt.Println(e + f)    //3  Judgment statement     if s == " Lin daiyu " {        fmt.Println("111")    } else {        fmt.Println("222")    }    //4  Loop statement     for i := 0; i < 5; i++ {        fmt.Println(i)    }    /*for true {        fmt.Println(" Sister Lin ")    }*/    // 7 Function call     var res int = max(a, d)    fmt.Println(res)    // 9 Array     var arr = [4]int{1, 24, 45, 6}    fmt.Println(arr)    i2 := arr[0]    fmt.Println(i2)    for i := 0; i < len(arr); i++ {        fmt.Println(arr[i])    }    for i3 := range arr {        fmt.Println(i3)    }    //10 Memory address     var m int = 23    //& yes go To address symbol in     Memory address     fmt.Println("m The address value in memory is ：", &m) //m The address value in memory is ： 0xc000018140    //11 The pointer ： A pointer variable points to the memory address of a value .    //12 Statement     //var r *float32    // Defining pointer variables .    var m1 int = 12    // Assign values to pointer variables .    var p *int // The pointer     fmt.Println("m1 The address value in memory is ", m1)    fmt.Println("p The address value in memory is ：", &p)    // Access the value pointing to the address in the pointer variable .    p = &m1 // The pointer points to 12    // Accessing values through pointers     fmt.Println("p Value ：", *p)    // Null pointer     var point *int             // according to for Cycle to understand     fmt.Println(" Null pointer ：", point) // Null pointer ： <nil>    //14  Instantiate a structure     fmt.Println(" New structure ：", Books{" Cao xueqin ",        " A dream of red mansions ", " philology ", 1})    // Instantiate a structure type （ Create objects ）    var Book1 Books    var Book2 Books    //get set Method to assign a value to a property     Book1.title = " Journey to the west "    Book1.anthor = " Wu chengen "    Book2.book_id = 1333    Book2.subject = " War class "    fmt.Println(Book1)    fmt.Println(Book2)    // Structure as function parameter     print(Book2)    //15 section , Expand the capacity of the array （ It's like a dynamic array ）    var slice []int = make([]int, 3)    slice = make([]int, 3)       // Abbreviation     slice = []int{1, 3, 5}       //init    fmt.Println(slice)           //[1 3 5]    var nums = make([]int, 3, 5) //t,len,cap    printMethod(nums)            //3 5 [0 0 0] Empty section nil    // Slice off     /*var array = [5]int{1, 2, 1, 3, 8}    var slice01 = make(arr, 4, 6)*/    // Create slices     slice01 := []int{1, 2, 1, 3, 8}    printMethod(slice01)    fmt.Println(" Original slice ", slice01) // Original slice  [1 2 1 3 8]    fmt.Println(" Print from index 1-4 All elements of , contain 1, But does not contain 4", slice01[1:4])    //append()()    var nums01 []int    // Define a slice     printMethod(nums01) //0 0 []    nums01 = append(nums01, 1)    nums01 = append(nums01, 6)    fmt.Println(nums01) //[1 6]    //copy()    slice02 := make([]int, len(nums01), cap((nums01))*2)    fmt.Println(slice02)    copy(slice02, nums01) //nums01 copy to slice02    printMethod(slice02)  //2 4 [1 6]    //16 enhance for loop     var array01 = []int{1, 2, 1, 3, 8}    for i3 := range array01 {        fmt.Println(i3)    }    map1 := make(map[int]float32)    map1[0] = 1.0    map1[1] = 2.0    map1[2] = 3.0    map1[3] = 4.0    map1[4] = 1.0    for key, val := range map1 {        fmt.Println(key, val)    }    for key := range map1 {        fmt.Println(key)    }    for _, val := range map1 {        fmt.Println(val)    }}func printMethod(num []int) {    fmt.Println(len(num), cap(num), num)}func print(books Books) {    fmt.Println(books.book_id)    fmt.Println(books.subject)    fmt.Println(books.title)    fmt.Println(books.anthor)    //17map aggregate     var map2 map[string]string    map2 = make(map[string]string)    map2[" Rongguofu "] = " Jia Baoyu "    map2[" Ning Guofu "] = " Jia Xichun "    fmt.Println(map2) //map[ Ning Guofu : Jia Xichun   Rongguofu : Jia Baoyu ]    delete(map2, " Ning Guofu ")    fmt.Println(map2) //map[ Rongguofu : Jia Baoyu ]    //18 Recursive function     //method() //fatal error: stack overflow    //Go  Language supports recursion . But when we use recursion , Developers need to set exit conditions , Otherwise, recursion will fall into an infinite loop .    // Recursive functions are very useful for solving mathematical problems , It's like calculating factorials , Generating Fibonacci series, etc .    fmt.Println("12 The factorial is ：", Factorial(12)) //479001600    for i := 0; i < 10; i++ {        fmt.Println(fibonacci(i)) //0 1 1 2 3        //5        //8        //13        //21        //34    }    //19 Type conversion     var a1 int = 17    var b1 int = 5    var res float32    res = float32(a1) / float32(b1)    fmt.Println(res) //3.4    // Implicit conversion is not supported , That is, big to small     //20go Language interface     var red Red    red = new(NingRed)    red.sleep()    red = new(RongRed)    red.sleep()    // Error handling     // The denominator is not 0    if result, errorMsg := Divide(4, 2); errorMsg == "" {        fmt.Println(result)    }    // The denominator is 0    if _, errorMsg := Divide(2, 0); errorMsg != "" {        fmt.Println(errorMsg)    }    //21go Concurrent     go say(" Jia Baoyu ") //go Must be in say Before call, Otherwise, it will always be say    say(" Lin ")      // Execute the above code , You'll see the output  hello  and  world    //  There is no fixed order . Because they are two  goroutine  In execution ：    // passageway     // establish channel    chdemo := make(chan int)    fmt.Println(chdemo) //0xc00018a000    s := []int{1, 2, 4, 5, 6}    ch := make(chan int)    go sum(s[:len(s)/2], ch)    go sum(s[len(s)/2:], ch)    m, n := <-ch, <-ch    fmt.Println(m, n, m+n)    sum(s, ch) //all goroutines are asleep - deadlock!    // buffer     /*         The channel with buffer allows the data transmission of the sender and the data acquisition of the receiver to be in an asynchronous state ,         In other words, the data sent by the sender can be put in the buffer , You can wait for the receiver to get the data , Instead of requiring the receiver to get the data immediately .*/    ch02 := make(chan int, 2)    ch03 := make(chan int, 3)    ch02 <- 4    ch03 <- 6    fmt.Println(<-ch02)    fmt.Println(<-ch03)    // Traversal channel     c := make(chan int, 10)    go itator(cap(c), c)    for i := range c{        fmt.Println(i)    }}func itator(a int, ch chan int) {    x, y := 1, 2    for i := 0; i < a; i++ {        ch <- x        x, y = y, x+y    }    close(ch)}func sum(arr []int, ch01 chan int) {    sum := 0    for i5 := range arr {        sum += i5        ch01 <- sum // hold sum Assign to ch01    }}func say(s string) {    for i := 0; i < 5; i++ {        time.Sleep(time.Millisecond * 100)        fmt.Println("---", s)    }}// Define an error structure type errorDemo struct {    demo1 int    demo2 int}func (de *errorDemo) Error() string {    strFormat := `       0 Cannot be used as denominator        demo1 = %d       demo2 = 0`    return fmt.Sprintf(strFormat, de.demo1)}func Divide(a3 int, b3 int) (result int, errorMsg string) {    if b3 == 0 {        data := errorDemo{            demo1: a3,            demo2: b3,        }        errorMsg = data.Error()        return    } else {        return a3 / b3, ""    }}type Red interface {    sleep()}type NingRed struct {}func (ningRed NingRed) sleep() {    fmt.Println(" There is ningguofu in the dream of Red Mansions , Shi Xiangyun lies drunk with peony root ")}type RongRed struct {}func (rongRed RongRed) sleep() {    fmt.Println(" There is Rongguo mansion in the dream of Red Mansions , Yang Fei plays with butterflies in the teary Pavilion ")}func fibonacci(n int) int {    if n < 2 {        return n    }    return fibonacci(n-2) + fibonacci(n-1)}func Factorial(n uint64) (result uint64) {    if n > 0 {        result = n * Factorial(n-1)        return result    }    return 1}func method() {    method()}//13 Structure （ amount to java Objects in the ）type Books struct {    // Structure definition needs to use  type  and  struct  sentence .struct    // Statement to define a new data type , A structure has one or more members .type  Statement sets the name of the structure . The format of the structure is as follows ：    // Defining a structure cannot use var    anthor  string    title   string    subject string    book_id int}// 6 Function declaration func max(num1, num2 int) int {    /*  Declare local variables  */    var result int    if num1 > num2 {        result = num1    } else {        result = num2    }    return result}

author ： Tianlu burning Chenopodium

Game programming , A game development favorite ~

If the picture is not displayed for a long time , Please use Chrome Kernel browser .