compare 2 haschtables

[Guest]

Hi,

what is the best way to compare 2 haschtables contatining objects. the
objects has 2 property, name & value. I need to print out the differences

 

[Guest]

You have to override the Object.Equals method. Attached is an example using
IEqualityComparer.

http://msdn2.microsoft.com/en-us/library/7b3y50ay(d=ide).aspx

 

[Guest]

hi,

ok, but in this case I will only know if there are equal or not.... I need
more than that.. I have to print out all the defferences between the 2
haschtables.. all diffrences in objects.

 

[Jay B. Harlow [MVP - Outlook]]

LZ,
I would probably define a 3rd hashtable contains a "union" of the first two
hash tables. This "union" would be a special object that contains name,
value1 (from hash 1) and value2 (from hash 2).

When adding the first hash table I would update the value1 properties, when
adding the second hash table I would update the value2 properties.

Then I would remove entries where value1 = value2.

I would then print out all the entries in this 3rd hashtable...

If that made no sense? I will try to post an example this evening.

--
Hope this helps
Jay B. Harlow [MVP - Outlook]
..NET Application Architect, Enthusiast, & Evangelist
T.S. Bradley - http://www.tsbradley.net


| hi,
|
| ok, but in this case I will only know if there are equal or not.... I need
| more than that.. I have to print out all the defferences between the 2
| haschtables.. all diffrences in objects.
| --
| LZ
|
|
| "Lamis" wrote:
|
| > Hi,
| >
| > what is the best way to compare 2 haschtables contatining objects. the
| > objects has 2 property, name & value. I need to print out the
differences
| > --
| > LZ

 

[Guest]

Lamis,
Attached is a sample of what both Jay and I were explaining.

Jared

class Program
{
static void Main(string[] args)
{
Hashtable customersWithCheckingAccounts = new Hashtable();
Hashtable customersWithSavingsAccounts = new Hashtable();
Hashtable customersThatDontHaveBothCheckingAndSavings = new
Hashtable();

LoadAccounts(
customersWithCheckingAccounts,
customersWithSavingsAccounts
);

MyHashComparer comparer = new MyHashComparer();

PrintHeader("Default comparer action");

comparer.Compare(
customersWithCheckingAccounts,
customersWithSavingsAccounts);

PrintHeader("Difference table enumeration");

customersThatDontHaveBothCheckingAndSavings =
comparer.GetDifferences(
customersWithCheckingAccounts,
customersWithSavingsAccounts);

foreach (DictionaryEntry entry in
customersThatDontHaveBothCheckingAndSavings)
{
Console.WriteLine(((MyDataObject)entry.Value).ToString());
}

Console.ReadLine();
}

static void PrintHeader(string message)
{
string sep = new string('*', 50);
Console.WriteLine();
Console.WriteLine(sep);
Console.WriteLine(message);
Console.WriteLine(sep);
Console.WriteLine();
}

static void LoadAccounts(Hashtable checking, Hashtable savings)
{
string customerName;
string accountNumber;
MyDataObject dataObject;
for (int i = 1; i < 30; i++)
{
if (i % 2 == 0)
{
customerName = string.Format("John {0}. Public",
GetInitial(i));
}
else
{
customerName = string.Format("Jane {0}. Public",
GetInitial(i));
}

accountNumber = string.Format("500000{0}", i);
dataObject = new MyDataObject(customerName, accountNumber);
checking.Add(dataObject.ToString(), dataObject);
if (i % 3 != 0)
{
savings.Add(dataObject.ToString(), dataObject);
}
}
}

private static string GetInitial(int i)
{
while (i > 26)
{
i -= 26;
}
return new string((char)(64 + i), 1);

}

}

public sealed class MyHashComparer
{
delegate void MyDataObjectAction(MyDataObject dataObject);
private Hashtable _differences;

public void Compare(Hashtable a, Hashtable b)
{
// Default to print differences.
MyDataObjectAction action = new
MyDataObjectAction(PrintDifferences);
Compare(a, b, action);
}
private void Compare(Hashtable a, Hashtable b, MyDataObjectAction
action)
{
IEnumerator iter = a.GetEnumerator();
while (iter.MoveNext())
{
MyDataObject dataObject =
(MyDataObject)((DictionaryEntry)iter.Current).Value;
if (b.ContainsValue(dataObject) == false)
{
action.Invoke(dataObject);
}
}
}


public Hashtable GetDifferences(Hashtable a, Hashtable b)
{
_differences = new Hashtable();
MyDataObjectAction action = new
MyDataObjectAction(BuildDifferences);
Compare(a, b, action);
return _differences;
}

private void BuildDifferences(MyDataObject dataObject)
{
_differences.Add(dataObject.ToString(), dataObject);
}
private static void PrintDifferences(MyDataObject dataObject)
{
Console.WriteLine(dataObject.ToString());
}

}

public class MyDataObject
{
private MyDataObject() { }
public MyDataObject(string name, string value)
{
_name = name;
_value = value;
}

private string _name;

public string Name
{
get
{
if (_name == null)
{
return "<Null>";
}
return _name;
}
set
{
_name = value;
}
}
private string _value;

public string Value
{
get
{
if (_value == null)
{
return "<Null>";
}
return _value;
}
set { _value = value; }
}


public override bool Equals(object obj)
{
if (obj is MyDataObject)
{
MyDataObject dataObject = (MyDataObject)obj;
return (
this._name.Equals(dataObject.Name) &&
this._value.Equals(dataObject.Value)
);
}
return false;
}
public override int GetHashCode()
{
return this.ToString().ToLower().GetHashCode();
}

public override string ToString()
{
return (
string.Format("{0}:{1}", this.Name, this.Value)
);
}
}