如何制作锯齿状索引器

Question

I have seen jagged indexers somewhere and would like to know how to make them work.

I know I can do the following:

class foo
{
    public string this[int i1]
    {
        get{ return GetString(i1); }
    }

    public string this[int i1, int i2]
    {
        get{ return GetString(i1) + GetString(i2); }
    }
}

So that:

string s1 = foo[5];
string s2 = foo[12,8];

The question is, how do I define the indexer to do...

string s2 = foo[12][8];

If possible (and otherwise unclear), I would also appreciate the setter definition.

foo[12][8] = "qwerty";

Answer 1

Derrick Shepard's answer seems correct, however I had a few notes for you:

With your current methods:

public string this[int i1]
public string this[int i1, int i2]

foo[12][8] would parse equivalently to (foo[12])[8] ; you'd be getting string foo[12] and then getting it's 9th character.

If you're willing to change your first method (the indexer with a single argument), you could consider returning an object which would, in turn, provide another indexer.

Answer 2

I hope this is what you are looking for:

class foo
{
    private string[][] collection = new string[2][];

    public string[] this[int index]
    {
        get
        { 
            return collection[index]; 
        }
        set
        {
            collection[index] = value;
        }
    }
}

and then:

string s1 = foo[1][0];
foo[1][0] = s1;

I was happy when I founded this but personally for me is quite confusing because getter and setter are weird. It looks like if collection is 1D array and not jagged.