[Qt-interest] QString and UNICODE: size determination

[Constantin Makshin]

QString *always* stores Unicode characters, so the amount of memory used  
by QString's contents is "str.size() * 2" or, what should be even better  
(forward compatibility, etc.), "str.size() * sizeof(QChar)".

On Wed, 08 Jul 2009 20:16:15 +0400, Bob Hood <bhood2 at comcast.net> wrote:
> I want to verify that this is the best way to do this.  If there's a
> better way, please feel free to correct me.
>
> I'm using a QString to store data that I'm going to use with direct
> Windows API calls in my Qt application.  I'm setting/clearing a Windows
> Registry key.  The call to these functions requires a wchar_t* and a
> size.  QString returns a size(), but it is only returning the number of
> characters in the string, not the actual number of bytes that are
> consumed by the string.
>
> In order to determine this, I'm making an assumption that the size()
> value can be multiplied by a factor of 2 in order to get the correct
> length.  For example:
>
>     [...]
>         int len = path_str.size();
>     #ifdef UNICODE
>         len *= 2;
>     #endif
>         RegSetValueEx(hkey,label_str.utf16(),0,REG_SZ,(const
> LPBYTE)path_str.utf16(),len);
>     [...]
>
> Is this the best way of determining the actual memory footprint of the
> data in a QString?

-- 
Constantin "Dinosaur" Makshin