从博客golang数组切片和字符串

Question

type path []byte

func (p path) ToUpper() {
    for i, b := range p {
        if 'a' <= b && b <= 'z' {
            p[i] = b + 'A' - 'a'
        }
    }
}

func main() {
    pathName := path("/usr/bin/tso")
    pathName.ToUpper()
    fmt.Printf("%s
", pathName)
}

[Exercise: Convert the ToUpper method to use a pointer receiver and see if its behavior changes.]
how to use a pointer method ? i have tried to dereference *p and tried to delete i from range but it keeps saying mismatched types.

Answer 1

Since path is a type defined on a []byte which happens to be a slice, there is no need to use a pointer receiver since slice types are already reference types.

However, if a pointer receiver is required, you'll need to dereference the pointer value everywhere in your method to get the underlying slice value:

func (p *path) ToUpper() {
    for i, b := range *p { // dereference p with a * to get the
                           // underlying []byte slice
        if 'a' <= b && b <= 'z' {
            (*p)[i] = b + 'A' - 'a' // derefernce p here as well
        }
    }
}

Working code: https://play.golang.org/p/feqeAlb80z