And I fond that when I don't Sort() first,
al.AddRange ...
al.Reverse();
Console.WriteLine(al.BinarySearch("this"));
displays 2, a right number.
What have the Sort() and Reverse() done with the ArrayList?
Can anyone tell some inner mechanism about this?
Thx.
On 4月27日, 下午5时41分, Jingle <[email protected]> wrote:
> Thank you for the answer.
> But Why The
>
> al.AddRange ...
> al.Sort();
> al.Reverse();
> Console.WriteLine(al.BinarySearch("this"));
> displays -7
>
> al.AddRange ...
> al.Sort();
> al.Reverse();
> al.Reverse();
> Console.WriteLine(al.BinarySearch("this"));
> displays 4 ?
> The different is just one more al.Reverse().
>
> On 4月27日, 下午4时47分, Jamie Fraser <[email protected]> wrote:
>
>
>
> > Generally when using a BinarySort, a negative number indicates that
> > the element wasn't found. The reason for the negative -X rather than
> > -1 is because the sort returns the element it "got to" during its
> > search before it realised that the element wasn't present.
>
> > On Tue, Apr 27, 2010 at 3:25 AM, Jingle <[email protected]> wrote:
> > > Hi All,
> > > I'm learning MCTS 70-536. These are some codes from Chapter 4:
>
> > > ArrayList al = new ArrayList();
> > > al.AddRange(new string[] { "Hello", "world", "this", "is", "a",
> > > "test" });
> > > Console.WriteLine(al.BinarySearch("this"));
>
> > > It displays 2 . but when I change the code to this:
>
> > > ArrayList al = new ArrayList();
> > > al.AddRange(new string[] { "Hello", "world", "this", "is", "a",
> > > "test" });
> > > al.Sort();
> > > al.Reverse();
> > > Console.WriteLine(al.BinarySearch("this"));
>
> > > It displays -7 . (yet when I add one more "al.Reverse()" into the
> > > code, it displays 4 )
>
> > > I've tested that only the code above gets a nagative number, other
> > > groups by some "al.Sort" and some "al.Reverse" all display a right
> > > number.
> > > Anyone who can help to explain ? Thanks!
>
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