Re: [Vala] string <-> bytes conversion in Vala

[Anatol Pomozov <anatol pomozov gmail com>]

Hi

On Thu, Dec 23, 2010 at 12:37 AM, Anatol Pomozov
<anatol pomozov gmail com> wrote:
> Hi,
>
> I manipulate with strings in my application such as storing/reading
> to/from binary files. And I need to convert a string to/from array of
> bytes. What is the best way of doing it in Vala?
>
> Looking into string class http://valadoc.org/glib-2.0/string.html I
> see a method called string#to_utf8() that converts string to array of
> chars. But I cannot find any other methods.
>
> So I have 2 questions:
>  - How to convert a string to array of chars in encoding different
> from UTF8. Something like this one
> http://download.oracle.com/javase/6/docs/api/java/lang/String.html#getBytes(java.nio.charset.Charset)
>  - How to convert array of chars/uint8 back to string? Like this one
> http://download.oracle.com/javase/6/docs/api/java/lang/String.html#String(byte[],
> java.nio.charset.Charset)

I think I found a way to convert string to bytes in Vala. Actually it
is as simple as casting string to char* and back. Under the hood
strings in vala is just a pointer to char.

Here is an example that shows it:

  string hello = "abcd";
  char* ch = (char*) hello;
  stdout.printf("%c\n", ch[1]); // Second char, that is 'b'

  char[] bytes = new char[4]; // 3 symbols and null-terminator
  bytes[0] = '1';
  bytes[1] = '2';
  bytes[2] = '3';
  bytes[3] = 0;
  string str = (string)bytes;
  stdout.printf(@"$str\n");
  stdout.printf("%d\n", (int)str.length); // Prints '3'

WRT question 'how to convert strings to different encodings' I think
this should help
http://library.gnome.org/devel/glib/unstable/glib-Character-Set-Conversion.html
I haven't it used though.