On Monday, 22 August 2016 11:51:59 UTC-4, JC wrote:
>
> Given:
>
> func main() {
> r := 'a'
> s := "a"
> fmt.Println(r)
> fmt.Println(s)
> }
>
> My very possibly incorrect understanding is that the rune r holds a
> Unicode code-point encoded with UTF-8 and stored as integer value, in this
> case 97, as type int32.
>
The rune r holds the Unicode code point 97 directly, without an encoding.
An encoding is a mapping from code points to byte sequences. Since there
are no bytes here, there is no encoding. A rune is just a number.
> s is of type string, and contains a code-point encoded by UTF-8, but
> which will be stored in a slice of type byte (which will use just one
> uint8 in this case). Assuming that is all correct, then my questions are:
>
A string is an immutable finite sequence of bytes. This string contains
the UTF-8 encoding of the single code point 'a', and that encoding consists
of the single byte 97. Code points less than 128 are encoded using a
single byte, and are thus compatible with ASCII.
> 1. Will the rune / any rune always use 32 bits?
>
Yes.
> 2. Why does printing r output the integer value, but printing s yield the
> code-point itself?
>
Println formats all numbers in decimal by default, and rune is simply an
alias for int32.
Println prints a string by copying its bytes to stdout. In this case, it's
just the single byte 97. The terminal prints this byte as 'a'. For more
complex code points (values > 127), the UTF-8-encoded string would contain
multiple bytes, and the terminal would decode these back into a single code
point and display the appropriate glyph.
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