CODEWITHSUNDEEP
c#
Real Bite of Life
Real Bite of Life

Reputation: 93

Listview item sort

I have several columns in a listview but I am just so dummb to think up a logical sorting method to both sort items out alphabetically and numerically. Because in case of numerical values I'd like a column's content such as:

  
111    
13   
442  
23   
214

to be:

 
13  
23  
111  
214  
442

My current sorting class looks like this:

class itemsorter:IComparer
{ 
    public int compare (object a, object b)
    {
       return string.compare(((lvitem)a).text,((lvitem)b).text));
    }
}

Upvotes: 0

Views: 635

Answers (2)

JKhuang
JKhuang

Reputation: 1553

As ziesemer said, you can take my sample code as below, hope this will give you a hand.

class itemsorter : IComparer
{
    public int compare(object a, object b)
    {
        int resultA, resultB;
        bool markA = int.TryParse(((lvitem)a).text, out resultA);
        bool markB = int.TryParse(((lvitem)b).text, out resultB)

        // They are number.
        if (markA && markB)
        {
            if (resultA > resultB)
                return 1;
            else if (resultA < resultB)
                return -1;
            else
                return 0;
        }


        // a can convert to number,
        // b can't.
        if (markA && !markB)
        {
            return 1;
        }

        // b can convert to number,
        // a can't.

        if(!markA && markB)
        {
            return -1;
        }

    }
}

Upvotes: 0

ziesemer
ziesemer

Reputation: 28687

Parse your Strings to numbers before doing the comparison, in which case you can simply return the difference of the 2 numbers as your result from the compare method.

As it sounds like you still want to sort both alphabetical and numerical values, this would have to be a combined, hybrid approach with the above - such that numbers are sorted against numbers, and alphabetical values with alphabetical. You'd just need to choose which takes precedence, such that either numerical or alphabetical values always come first - necessary to maintain a stable and reflexive sort. (For example, if a is a number, and b is a non-number, return 1. If a is a non-number, and b is a number, return -1. Else, they must be of equal types, and then you can defer to the type-specific sorting.)

Upvotes: 1

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