go基础学习day3

命名

包：小写字母

文件：小写用“_“分隔

结构体：驼峰命名法

接口：用er作为后缀

变量：小写，驼峰分隔

常量：大写，“_”分隔

单元测试：文件xxxx_test  函数一般用TEST开头

变量

声明后必须使用，匿名变量不想使用可以用 "_"

package main

import "fmt"

func getName() (string, int) {
    return "tom", 20
}

func main() {
    /*  var name string
        var age int
        var m bool */

    /* var (
        name string
        age  int
        m    bool
    )
    name = "wty"
    age = 20
    m = true */

    //初始化
    /* var name string = "wty"
    var age int = 20
    var m bool = true */

    //类型推断
    /*  var name = "wty"
        var age = 20
        var m = true */

    //批量初始化
    // var name, age, m = "wty", 20, true

    //短变量声明,只能在main()下使用
    // name := "wty"

    /*  fmt.Printf("name: %v\n", name)
        fmt.Printf("age: %v\n", age)
        fmt.Printf("m: %v\n", m) */

    //匿名变量,和上面函数一起使用
    name, age := getName()
    fmt.Printf("name: %v\n", name)
    fmt.Printf("age: %v\n", age)
}

常量定义

ackage main

import "fmt"

func main() {
    const PI = 3.14
    fmt.Printf("PI: %v\n", PI)

    const (
        A = 100
        B = 200
    )
    fmt.Printf("A: %v\n", A)
    fmt.Printf("B: %v\n", B)

    const w, h = 11, 22
    fmt.Printf("w: %v\n", w)
    fmt.Printf("h: %v\n", h)
    
    //iota可以改变数值的常量类似于i++，从0开始
    /* const (
        a1 = iota   //0
        a2 = iota   //1
        a3 = iota   //2
    ) */

    /* const (
        a = iota    //0
        _           //1
        b = iota    //2
    ) */

    const (
        a = iota    //0
        b = 100        //100
        c = iota    //2
    )
    fmt.Printf("a: %v\n", a)
    fmt.Printf("b: %v\n", b)
    fmt.Printf("c: %v\n", c)
}

数据类型

package main

import "fmt"

func main() {
    /* var name string = "wty"
    var age int = 20
    var b bool = true
    fmt.Printf("%T\n", name) //%T代表类型，\n换行
    fmt.Printf("%T\n", age)
    fmt.Printf("%T\n", b) */

    /* a := 100
    p := &a
    fmt.Printf("%T\n", p)   //输出*int指针 */

    /*  a := [...]int{1, 2, 3, 4, 5}    //[5]int数组
        fmt.Printf("%T\n", a) */

    a := []int{1, 2, 3, 4, 5} //[]int切片类型
    fmt.Printf("%T\n", a)
}