problem in porting QString::at(index)
thiago at kde.org
Tue Oct 11 21:15:36 BST 2005
David Faure wrote:
>On Tuesday 11 October 2005 15:48, Andreas Gungl wrote:
>> I've found a problem in a changed semantic of QString::at(0) which
>> seemed to return '\0' in Qt3 for an empty string. Now we run into an
>> assertion for 0 <= i < size() although the Qt4 docu says about
>> QString::size(), that at position size() of a QString there is ever
>> placed a '\0'.
>From what you say there is clearly a mismatch between the Qt4 behavior
> and the Qt4 documentation, so you should send this mail to
> qt-bugs at trolltech.com
I don't agree. It just looks like a misinterpretation of the docs:
const QChar QString::at ( int i ) const
Returns the character at index position i in the string.
i must be a valid index position in the string (i.e., 0 <= i < size()).
See also operator().
int QString::size () const
Returns the number of characters in this string.
The last character in the string is at position size() - 1. In addition,
QString ensures that the character at position size() is always '\0', so
that you can use the return value of data() and constData() as arguments
to functions that expect '\0'-terminated strings.
So, it means you can use data() and constData() and read U+0000-terminated
strings, but you're not allowed to use at() to access it.
For this case, I recommend to use constData() directly. The difference
between doing that and using QString::at is the bounds check.
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
PGP/GPG: 0x6EF45358; fingerprint:
E067 918B B660 DBD1 105C 966C 33F5 F005 6EF4 5358
1. On frumscafte, hwonne time_t wæs náht, se scieppend þone circolwyrde
wundorcræftlíge cennede and seo eorðe wæs idel and hit wæs gód.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Size: 189 bytes
Desc: not available
More information about the kde-core-devel