Is it possible for a function to change the size of a slice of string array declared elsewhere? golang

I would like to remove an element from the slice in place. But when I do this I end up producing two empty elements in the underlying array.
I already searched here, here

package main

import "fmt"

//String remove adjacent duplicates from a string array
func rmDup(str []string) []string {
	for i := 1; i < len(str); i++ {
		if str[i] == str[i-1] {
			copy(str[i:], str[i+1:])
			str[len(str)-1] = ""
			str = str[:len(str)-1]
		}
	}
	return str
}

func main() {

	str := []string{"dog", "cat", "cat", "mouse", "mouse", "zebra", "zebra"}

	fmt.Println(str)
	newstr := rmDup(str)
	fmt.Println(str)
	fmt.Println(newstr)
	fmt.Println(len(str), cap(str), "final")
	fmt.Println(len(newstr), cap(newstr), "final")
}

Is there any way that str in main can return the size and capacity defined in rmDup()
1: https://github.com/golang/go/wiki/SliceTricks
2: https://blog.golang.org/go-slices-usage-and-internals

It turned out that I was able to find the answer myself. Since the Go language performs function calls by value it is impossible to change a slice declared in another scope, except using pointers.

package main

import "fmt"

//String remove adjacent duplicates from a string array
func rmDup(str *[]string) []string {
 var s = *str
 for i := 1; i < len(s); i++ {
	if s[i] == s[i-1] {
		copy(s[i:], s[i+1:])
		s[len(s)-1] = ""
		s = s[:len(s)-1]
	}
}
*str = s
return s
}

func main() {

  str := []string{"dog", "cat", "cat", "mouse", "mouse", "zebra", 
  "zebra"}

  fmt.Println(str)
  newstr := rmDup(&str)
  fmt.Println(str)
  fmt.Println(newstr)
  fmt.Println(len(str), cap(str), "final")
  fmt.Println(len(newstr), cap(newstr), "final")
}

Output:

[dog cat cat mouse mouse zebra zebra]
[dog cat mouse zebra]
[dog cat mouse zebra]
4 7 final
4 7 final

> Is there any way that str in main can return the size and capacity
> defined in rmDup()?

For example,

package main

import "fmt"

//String remove adjacent duplicates from a string array
func rmDup(str []string) []string {
	for i := 1; i < len(str); i++ {
		if str[i] == str[i-1] {
			copy(str[i:], str[i+1:])
			str[len(str)-1] = ""
			str = str[:len(str)-1]
		}
	}
	return str
}

func main() {
	str := []string{"dog", "cat", "cat", "mouse", "mouse", "zebra", "zebra"}
	fmt.Println(len(str), cap(str), str)
	str = rmDup(str)
	fmt.Println(len(str), cap(str), str)
}

Output:

7 7 [dog cat cat mouse mouse zebra zebra]
4 7 [dog cat mouse zebra]

> i meant in place without the function rmDup() having to return
> anything.

For example,

package main

import "fmt"

//String remove adjacent duplicates from a string array
func rmDup(str *[]string) {
	s := *str
	for i := 1; i < len(s); i++ {
		if s[i] == s[i-1] {
			copy(s[i:], s[i+1:])
			s[len(s)-1] = ""
			s = s[:len(s)-1]
		}
	}
	*str = s
}

func main() {
	str := []string{"dog", "cat", "cat", "mouse", "mouse", "zebra", "zebra"}
	fmt.Println(len(str), cap(str), str)
	rmDup(&str)
	fmt.Println(len(str), cap(str), str)
}

Output:

7 7 [dog cat cat mouse mouse zebra zebra]
4 7 [dog cat mouse zebra]