GO-变量、常量以及与其他语言的差异01

待我称王封你为后i 2024-04-08 09:19 30阅读 0赞

## 编写测试程序 ##

1.源码文件以\_ *test结尾: xxx* test. go  
2.测试方法名以Test开头: func TestXXX(t \*testing.T) …\}

package try_test
    
    import "testing"
    
    func TestName(t *testing.T) {
        
       t.Log("My first try")
    }

## 实现Fibonacci数列 ##

1,1,2,3,5,8,13,

package fib
    
    import (
       "fmt"
       "testing"
    )
    
    func TestFibList(t *testing.T) {
        
       //var a = 1;
       //var b = 1;
       var (
          a int = 1;
          //b int = 1;
          b   = 1; // 俩个类型放一起,go有类型推断能力
       )
       /*a := 1
        b := 1*/ // 这样声明也ok
       fmt.Print(a)
       for i := 0; i < 5; i++ {
        
          fmt.Print(" ", b)
          tmp := a
          a = b
          b = tmp + a
       }
       fmt.Println()
    }

package fib
    
    import (
       "testing"
    )
    
    func TestFibList(t *testing.T) {
        
       //var a = 1;
       //var b = 1;
       var (
          a int = 1;
          //b int = 1;
          b   = 1; // 俩个类型放一起,go有类型推断能力
       )
       /*a := 1
       b := 1*/ // 这样声明也ok
       //fmt.Print(a)
       t.Log(a)
       for i := 0; i < 5; i++ {
        
          //fmt.Print(" ", b)
          t.Log(b)
          tmp := a
          a = b
          b = tmp + a
       }
       //fmt.Println()
    }

## 变量赋值 ##

与其他主要编程语言的差异

*  赋值可以进行自动类型推断
 *  在一个赋值语句中可以对多个变量进行同时赋值

// 交换值2种写法
    func TestExchange(t *testing.T) {
        
       a:=1
       b:=2
       //tmp:=a
       //a=b
       //b=tmp
       a,b=b,a
       t.Log(a, b)
    }

## 常量定义 ##

![在这里插入图片描述][050526252fa94b9aa0d863c3622ca279.png]

package constant_test
    
    import "testing"
    
    const (
       Monday = 1 + iota
       Tuesday
       Wednesday
    )
    
    func TestConstantTry(t *testing.T) {
        
       t.Log(Monday, Tuesday, Wednesday)
    }

Result:

=== RUN   TestConstantTry
        constant_try_test.go:12: 1 2 3
    --- PASS: TestConstantTry (0.00s)
    PASS

## 位与运算符(&) ##

const (
       Readable = 1 << iota
       Writable
       Executable
    )
    /**
    4.位与运算符(&)
    运算规则：两个数都转为二进制，然后从高位开始比较，如果两个数都为1则为1，否则为0。
    比如：129&128.
    129转换成二进制就是10000001，128转换成二进制就是10000000。从高位开始比较得到，得到10000000，即128.
     */
    func TestConstantTry1(t *testing.T) {
        
       t.Log(Readable, Writable, Executable)
       a := 1 // 0001
       t.Log(a&Readable == Readable,a&Writable == Writable,a&Executable==Executable)
       b := 7 // 0111
       t.Log(b&Readable == Readable,b&Writable==Writable,b&Executable==Executable)
    
    }

Result:

=== RUN   TestConstantTry1
        constant_try_test.go:18: 1 2 4
        constant_try_test.go:20: true false false
        constant_try_test.go:22: true true true
    --- PASS: TestConstantTry1 (0.00s)
    PASS

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[050526252fa94b9aa0d863c3622ca279.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/08/dae25f88329b45fe9664bd8bc3f27b20.png