使用func的语法Golang错误

Question

Why does the code below throw unexpected func error ? I see error ./func_correct.go:4: syntax error: unexpected func, expecting name

package main

func (st  *Stack)  Pop() int {
        v := 0
        for ix := len (st) - 1; ix >= 0; ix-- {
                if v = st[ix]; v != 0 {
                    st[ix] = 0
                    return v
                }
        }
        return 0
}

func main() {
   Pop()    
}

Answer 1

1. define Stack type

2. in main create a variable of it

3. call Pop on it

code:

package main

import "fmt"

type Stack []int

func (st Stack) Pop() int {
    v := 0
    for ix := len(st) - 1; ix >= 0; ix-- {
        if v = st[ix]; v != 0 {
            st[ix] = 0
            return v
        }
    }
    return 0
}

func main() {
    s := Stack{1, 2, 3, 4}
    i := s.Pop()
    fmt.Println(i)
}

https://play.golang.org/p/PSac-C0xJM