Array And Slice The Rust And Golang Style

Array and Slice is the basic element of a program in modern high-order programming language, but how different language deal with them? We will inspect the Golang and Rust way.

1. Array, the same kind of things in a sequence

Array have the following attribute:

• the size is know in compile time
• the type of all elements are the same
• you can not change the elements by default[Rust]

	a := [3]int{1, 2, 3}
	fmt.Println(a)
	a[1] = 4
	fmt.Println(a)

running result:

the array in golang can be changed.

    let rs_arr = [1,2,3];
    println!("{:?}", rs_arr);
    rs_arr[2] = 4;
    println!("{:?}", rs_arr);

running result:

the default(no mutable) array in rust can’t be changed in runtime.

2. Slice, the mask on an array

slice is more like a data struct, which contains:

• a pointer to the underline array element
• length of the slice
• capacity of the slice

type IntSlice struct 
{
    ptr   *int
    len, cap int
}

the follwing is two slices have the same underlying array:

A simple program in golang, delete adjecent duplicate word in a string:

func RemoveAdjacentDuplicateString(s []string) []string {
	dupnum := 0
	curpos := 1

	//dup adj never can happen
	if len(s) <= 1 {
		return s
	}

	for curpos < len(s)-dupnum {
		if s[curpos] == s[curpos-1] {
			copy(s[curpos-1:], s[curpos:])
			dupnum++
		} else {
			curpos++
		}
	}

	return s[:len(s)-dupnum]
}

3. Slice, the rust style

The following a code sneppet from “The Rust Programming Language”.

fn first_word(s: &String) -> &str {
    let bytes = s.as_bytes();

    for (i, &item) in bytes.iter().enumerate() {
        if item == b' ' {
            return &s[0..i];
        }
    }

    &s[..]
}

&s[0..i] is a slice reference to string.

4. Summary

Slice is more generally used than array, use it! :)