Preface

When learning a language, it's hard to avoid learning from the simplest program structure. When mastering another development language (such as the famous java), these things will look like a fish in water. I'll share some simple examples below.

Basic program structure

Quickly assign values to some variables

const (
    NUM1 = 1 + iota
    NUM2
    NUM3
    NUM4
)

//Output: 1, 2, 4, 8
func TestPrint(t *testing.T) {
    t.Log(NUM1, NUM2, NUM3, NUM4)
}

Fast implementation of some numerical exchange

//Numerical exchange
func TestExchange(t *testing.T) {
//You can also define variables like this: var aa int = 1
    a := 1
    b := 2
    t.Log(a, b)
    //Exchange value
    b, a = a, b
    t.Log(a, b)
}

Type conversion

//Name the type
type typeInt int64

func TestInt(t *testing.T) {
    var a int64 = 2
    var b int32 = 3
    //Type cannot be transferred
    //a = b
    var c = typeInt(3)

    t.Log(a, b, c)
}

Two ways to realize fibolacci sequence

//Fei Po La Chi
func TestFibList(t *testing.T) {
    var a int = 1
    var b int = 1
    t.Log(a)
    for i := 0; i < 5; i++ {
        t.Log(b)
        tmp := a + b
        a = b
        b = tmp
    }
}

//Fibolacci recursion
func TestFibRecursion(t *testing.T) {
    t.Log(FibRecursion(5))
}

func FibRecursion(i int) (result int) {
    if i == 1 || i == 2 {
        return 1
    }
    return FibRecursion(i-1) + FibRecursion(i-2)
}

Array comparison, different from java, is not a comparison pointer, which can compare values

//Array comparison
func TestCompareArray(t *testing.T) {
    a := [...]int{1, 2, 3, 4}
    b := [...]int{1, 2, 2, 4}
    c := [...]int{1, 2, 3, 4}
    t.Log(a == b) //false
    t.Log(a == c) //true
}

go also has a pointer, but I didn't look at it carefully. I just wrote an example to see the result

func TestPoint(t *testing.T) {
    var a int64 = 1
    var aPtr = &a
    t.Log(a, aPtr)// 1 0xc420018230
    //Printing class: int64 *int64
    t.Logf("%T %T", a, aPtr)
}

Default value of string

func TestString(t *testing.T) {
    //The default value is not java null
    var str string
    t.Log("+" + str + "+")//Output + +
}

for cycle

//There was no while in the for loop go
func TestFor(t *testing.T) {
    n := 5
    for n > 0 {
        t.Log(n)
        n--
    }
}

//For loop for bubble sorting
func TestForSort(t *testing.T) {
    a := [...]int{3, 5, 2, 6, 4, 8, 2, 9,1,23,2,34,4,55,11}
    for i := 0; i < len(a)-1; i++ {
        for j := 0; j < len(a)-i-1; j++ {
            if a[j] > a[j+1] {
                tmp := a[j]
                a[j] = a[j+1]
                a[j+1] = tmp
            }
        }
    }

    t.Log(a)//[1 2 2 2 3 4 4 5 6 8 9 11 23 34 55]

}

The condition judgment in go is very good

//compare
func TestCondition(t *testing.T){
    //You can assign conditional results to variables
    if a:=3>2;a{
        t.Log("3>2")
    }

    // GOOS is the running program's operating system target:
    // one of darwin, freebsd, linux, and so on.
    switch runtime.GOOS{
    //Bring break
    case "darwin":
        t.Log("darwin")
    case "freebsd":
        t.Log("freebsd")
    case "linux":
        t.Log("linux")
    default:
        t.Log("default")
    }

    switch  {
    case 4>2:
        t.Log("4>2")
    case 4<2:
        t.Log("4<2")

    }
}