Immutable strings

Why doesn’t this code compile?

s := "hello" s[0] = 'H' fmt.Println(s)

../main.go:3:7: cannot assign to s[0] 

Answer

Go strings are immutable and behave like read-only byte slices (with a few extra properties).

To update the data, use a rune slice instead.

buf := []rune("hello") buf[0] = 'H' s := string(buf) fmt.Println(s) // "Hello" 

If the string only contains ASCII characters, you could also use a byte slice.

See String functions cheat sheet for an overview of strings in Go.

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