Re: QSort.......

[Ralf Stephan]

Marie-Edith Bisset: 
> So my problem:
> I have an array of Value objects, which I would like to rank. In my
> program, the Value class is an object wrapper for integers.
> 
> The statement: 
> 
> [QSort sortObjectsIn: arrayOfDistance];
> 
> does not crash the program, but basically does nothing: the elements
> in the array are still in the same order.

This invokes Value::compare which is probably not defined.
This message has to be of the form int compare: (id) otherObject;

> The statement:
> 
> [QSort sortObjectsIn: arrayOfDistance using:M(getMyValue)];
> 
> where getMyValue is a function of the Value class returning the
> integer value of the object, does something (ie the elements in the
> array are in a different order), but does not rank the array in
> ascending order.

The values are probably interpreted as comparison results and so
this produces garbage behaviour.

> I have also written a comparison function which I put in the value
> class:
> 
> -(int)compareValue:value1:value2
>       {
>       int val1,val2;
>       val1=[value1 getMyValue];
>       val2=[value2 getMyValue];
>       return val1<val2?-1:val1!=val2;
>       }

The func has to be of type (PTRINT) func: (id) otherObject;
if I understand the source correctly.

In logzone (v.0.6 in anarchy) I have augmented the QSort source,
as I was also unable to get the other mechanisms to work but I will
revise it ASAP if Marcus gives a better answer to your query than
mine is <g>.


ralf
-- 
http://ME.IN-berlin.de/~rws/

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