Get element in List<T>

  • Thread starter Thread starter Luigi
  • Start date Start date
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Luigi

Hi all,
I have a List of object Column, and the class Column has 2 properties:
a name (string) and a enum (type, normal or total).

public class Column
{
private string columnName;
public string ColumnName
{
get { return columnName; }
set { columnName = value; }
}

public ColumnType columnType;
public enum ColumnType : short { Normal = 0, Total = 1 };

}

How can I obtain the element of the List having a "columnName" (so I can get
the type of this columnName)?

Thank a lot.
 
Luigi said:
Hi all,
I have a List of object Column, and the class Column has 2 properties:
a name (string) and a enum (type, normal or total).

public class Column
{
private string columnName;
public string ColumnName
{
get { return columnName; }
set { columnName = value; }
}

public ColumnType columnType;
public enum ColumnType : short { Normal = 0, Total = 1 };

}

How can I obtain the element of the List having a "columnName" (so I can get
the type of this columnName)?
Click to expand...

The List<T> class isn't indexed, so you have to do a linear search. You
can use .FindAll() or if you're using .NET 3.5, linq to objects using
..Where(filter), but both are doing a linear search, so you can also
simply use a foreach statement over the List<T>.

FB

--
------------------------------------------------------------------------
Lead developer of LLBLGen Pro, the productive O/R mapper for .NET
LLBLGen Pro website: http://www.llblgen.com
My .NET blog: http://weblogs.asp.net/fbouma
Microsoft MVP (C#)
------------------------------------------------------------------------
 
Luigi said:
Hi all,
I have a List of object Column, and the class Column has 2 properties:
a name (string) and a enum (type, normal or total).

public class Column
{
private string columnName;
public string ColumnName
{
get { return columnName; }
set { columnName = value; }
}

public ColumnType columnType;
public enum ColumnType : short { Normal = 0, Total = 1 };

}

How can I obtain the element of the List having a "columnName" (so I can
get
the type of this columnName)?
Click to expand...

For the structure of your code I'll assume C# 2.

You need the Find method of the List class and pass it a predicate
function:-

Column col = Columns.Find(delegate(Column c) { return c.ColumnName ==
"columnName"; });

In C# 3 it collapses to

Column col = Columns.Find(c => c.ColumnName == "columnName");

BTW, What other names are attached to a Column objects? IOW why not call
ColumnName simply Name?
 
Anthony Jones said:
For the structure of your code I'll assume C# 2.

You need the Find method of the List class and pass it a predicate
function:-

Column col = Columns.Find(delegate(Column c) { return c.ColumnName ==
"columnName"; });

In C# 3 it collapses to

Column col = Columns.Find(c => c.ColumnName == "columnName");

BTW, What other names are attached to a Column objects? IOW why not call
ColumnName simply Name?
Click to expand...

Perferct, thank you Anthony and Frans.

Luigi
 
Hi Anthony and Frans, a little variant.
My Column class has another property, a List<Column> (for example if a
column is a total column, and this list is its composition.

......
public List<Column> TotalComposition;
.......

How can I write a method that returns me the List<Column> composition for a
particular Column?

private static List<Column> GetTotalComposition(Column total)
{
....to implement
}

Thanks a lot.

Luigi
 
Luigi said:
Hi Anthony and Frans, a little variant.
My Column class has another property, a List<Column> (for example if a
column is a total column, and this list is its composition.

.....
public List<Column> TotalComposition;
......

How can I write a method that returns me the List<Column> composition for
a
particular Column?

private static List<Column> GetTotalComposition(Column total)
{
...to implement
}
Click to expand...

I'm afraid you've lost me. You're going to need to put some more detail and
code into this one.

What for example do you mean by 'composition'? So far if a Column has a
property called TotalComposition what is stopping you from just accessing
it? That probably makes no sense to you but that it'll be because I haven't
been able to make sense of the above.
 
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