[Qt-interest] Simple qSort() question

[Joshua Grauman]

Thanks to all for the helpful suggestions, I think either of these can 
work well.

Josh

> Hi,
>
>> I have three QStringLists that I would like to sort.
>> [...]
>
> Would you consider reorganising your data?
>
> Others have suggested having an intermediate mapping to translate the
> required sort order to the order of the data items, but my opinion is
> that that will get a bit messy.
>
> At the moment you have what looks to me like one list per column, and
> you wish to sort your rows on one column.
>
> I would suggest you store your data as rows, and sort those, keeping
> your associated data together.
>
> Two ways spring to mind.  One is with existing Qt classes - use a
> QStringList for each row (ie: with 3 entries, one per column), and a
> QMap< QString, QStringList > to store them - this sorts it for you, but
> random access to a specific row number means more work.
>
> The other way is to write a class to hold each row and a lessThan
> function for it which compares your sort field, then just use a single
> QList< MyRow > and sort it as you are doing now.
>
> In fact, I think it may be this simple:
>
> class MyRow
> {
> public:
>  QString a;
>  QString b;
>  QString c;
>  MyRow( const QString & x, const QString & y, const QString & z )
>    : a(x), b(y), c(z) {};
> };
>
> bool rowLessThan( const MyRow & r1, const MyRow & r2 )
> {
>  return r1.a < r2.a;  // sorts on first field
> }
>
> QList< MyRow > list;
> list.append( MyRow( "foo", "bar", "cheese" ) );
> ...
>
> qSort( list.begin(), list.end(), rowLessThan );
> cout << list[0].c << endl;
>
>
> Caveat emptor: I have not compiled or tested this! :-)
>
>
> Steve
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