Go编程——变量、函数导出与首字母大写

package main

import (
    "even"
    "fmt"
)

func main() {
    i:=even.I
    fmt.Printf("Is %d even? %v\n", i, even.Even(i))
}

package even

var I int = 123

 func Even(i int) bool {
    return i%2==0
}

func odd(i int) bool {
    return i%2!=0
}

fmt.Printf("Is %d even? %v\n", i, even.odd(i))

main.go:10: cannot refer to unexported name even.odd

type S struct {
    T1        //字段名字是 T1
    *T2       //字段名字是 T2
    P.T3      //字段名字是 T3
    x, y int  //字段名字是 x 和 y
}