How do I create an array of one item in Go?

Question

Let's say a function takes an array of strings:

func Join(strs []string) {
     ...
}

I have a single string:

a := "y'all ain't got the honey nut?"

How can I convert that string into an array?

Answer 1

The actual answer to your question is as simple as []string{"string"}, as miltonb said.

But what I wanted to point out is how easy it is to write and use a variadic function in Go, a function with a variable number of arguments.

You can change signature of your function to F(a ...string). Then, a is slice in the function F, and you can call it like F("a") and F("a", "b"). And when you actually have a slice or array, you can pass it to F by calling F(a...).

Not sure if this syntax fits your job, but I wanted to let you know about it as an option.

Answer 2

You can create a slice of one item using the following convention:

a := "y'all ain't got the honey nut?"
singleItemArray := []string{a}

strings.Join(singleItemArray);

Answer 3

The question as phrased actually references Arrays and Slices. The question text is about an array and the code is illustrating using a slice. Therefore there two questions are implied; pass a single item slice, and pass a single item array.

An array: var a [1]string A slice: var s []string

Passing a single item slice to the function:

func SliceFunc( slc []string) {
    fmt.Println(slc)
}

func main() {
    a := "stringy"
    SliceFunc( []string{a} )
    // or an actual array to the same function
    b := [...]string { "thingy" }
    SliceFunc( []string{b[0] )  
}

Passing a single item array to the function.

Here there is an issue, as an array has a fixed length and as a parameter to a function it cannot accept different length arrays so we are left with working function which has limited flexibility:

func ArrayFunc( arr [1]string) {
    fmt.Println(slc)
}

func main() {
    var a [1]string
    a[0] = "stringy"
    ArrayFunc( a )  
}

It seems that as a generalization sticking to slices is a more flexible solution.

(If you would like more on Slices and Arrays here one blog by Andrew Gerrand covering go slices usage and internals.)