Pass an argument to use with a foreach loop

[Mc_Topaz]

I want to pass an argument to a foreach loop. This to specify the foreach loop to loop through a collection in a specific way. See this code:

foreach (DataType instance in collection(argument))
{
// Do something
}

This is my test program:

class Program
{
static void Main(string[] args)
{
Cells cells = new Cells();

  foreach (Cell cell in cells)
  {
     Console.WriteLine(cell.Value);
  }
}

}

public class Cell
{
private string column;
private int row;
private string value;

public Cell(string column, int row, string value)
{
this.column = column;
this.row = row;
this.value = value;
}

public string Value
{
get { return value; }
set { this.value = value; }
}
}

public class Cells : IEnumerator, IEnumerable
{
private Cell[] cellList;
int position = -1;

public Cells()
{
cellList = new Cell[10]
{
new Cell("A", 1, "A:1"),
new Cell("A", 2, "A:2"),
new Cell("A", 3, "A:3"),
new Cell("A", 4, "A:4"),
new Cell("A", 5, "A:5"),

     new Cell("B", 1, "B:1"),
     new Cell("B", 2, "B:2"),
     new Cell("B", 3, "B:3"),
     new Cell("B", 4, "B:4"),
     new Cell("B", 5, "B:5"),
  };

}

public IEnumerator GetEnumerator()
{
return (IEnumerator)this;
}

public bool MoveNext()
{
position++;
return (position < cellList.Length);
}

public void Reset()
{
position = 0;
}

public object Current
{
get { return cellList[position]; }
}
}

Notice in the cellList array in the Cells class which is looped through in the Main()-method. I want to loop through all Cell instances in the list which has the column member set to "B". I would like to prefer to write it like this in the Main()-method:

class Program
{
static void Main(string[] args)
{
Cells cells = new Cells();

  foreach (Cell cell in cells("B"))
  {
     Console.WriteLine(cell.Value);
  }
}

}

or

class Program
{
static void Main(string[] args)
{
Cells cells = new Cells();

  foreach (Cell cell in cells.Column("B"))
  {
     Console.WriteLine(cell.Value);
  }
}

}

Is it possible to modify my test code to this? I'm not looking for this answer:

class Program
{
static void M

[OriginalGriff]

Yes, but not quite the way you have it. You would need to write a "Find(string s)" method (or similar) for your Cells class, which returns a list of each matching cell. This might defeat the purpose a bit, as it would move the "cell.Value.Contains(s)" into the method, rather than the foreach loop.

I have learnt that you can not make someone love you, all you can do is stalk them and hope they panic and give in. Apathy Error: Don't bother striking any key.

[Abhinav S]

Have a look at the AsQueryable() extension method. See here.

[Mc_Topaz]

I'm fine if I need to write:

cell.Value.Contains(s)

or something similar in the Cells class. I know I need to do some changes in the Cells class. I'm just wonder if I, in the Main()-method, can pass an argument in the foreach-loop condition, just like I stated it.

[sam]

Use LINQ !

[Luc Pattyn]

If you want to be able to do

foreach (Cell cell in cells.HavingColumn("B")) {
Console.WriteLine(cell.Value);
}

all you have to do is add a method HavingColumn(string columnName) to the Cell class, which returns a System.Collections.IEnumerable or a System.Collections.IEnumerable<T=Cell>; one way of implementing that is by creating a List<Cell>. FWIW1: this operation will be more expensive than simply adding a test inside your foreach; which is how the method will be implemented anyway (but then it is hidden from the external world). FWIW2: and that must be how LINQ does it; the easiest and most expensive approach. :)

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]

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I only read formatted code with indentation, so please use PRE tags for code snippets.

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I'm not participating in frackin' Q&A, so if you want my opinion, ask away in a real forum (or on my profile page).

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