How to slice a rune in Go

16 March 2015   0 comments   Go

Mind that age!

This blog post is 5 years old! Most likely, its content is outdated. Especially if it's technical.

Strangely this was hard. The solution looks easy but it took me a lot of time to get this right.

What I want to do is split a string up into a slice of parts. For example:

word := "peter"
for i := 1; i <= len(word); i++ {
    fmt.Println(word[0:i])
}

The output is:

p
pe
pet
pete
peter

Play here.

Now, what if the word you want to split contains non-ascii characters? As a string "é" is two characters internally. So you can't split them up. See this play and press "Run".

So, the solution is to iterate over the string and Go will give you an index of each unicode character. But you'll want to skip the first one.

word := "péter"
for i, _ := range word {
    if i > 0 {
        fmt.Println(word[0:i])
    }
}
fmt.Println(word)

You can play with it here in this play.

Now the output is the same as what we got in the first example but with unicode characters in it.

p
pé
pét
péte
péter

I bet this is obvious to the gurus who've properly read the documentation but it certainly took me some time to figure it out and so I thought I'd share it.

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