foreach with Generic Dictionary

Vadim — Sun, 30 Mar 2008 22:00:05 +0000

I decided to write this post because few people approached me with the question: “Is there a way to use foreach iteration statement with Dictionary object?”

The quick response is: “Yes, use KeyValuePair.”

However, it wasn’t enough and I had to show an example.

Before I will show an example here, I want to remind you that Dictionary class implements IDictionary interface that extends ICollection which in it turn is derived from IEnumerable. As we know every class that implements IEnumerable interface must implement the GetEnumerator method. And that is the reason why we can use foreach iteration statement.

Here’s the promised example.

// Create a Dictionary object and load it with values.
Dictionary<string, double> employeesWage = new Dictionary<string, double>();
employeesWage.Add("Tom", 20000);
employeesWage.Add("John", 15200);
employeesWage.Add("Chris", 35000);
employeesWage.Add("Brian", 38000);
  
// Enumerate and display
foreach (KeyValuePair<string, double> pair in employeesWage)
  Console.WriteLine("{0} makes {1:C}", pair.Key, pair.Value);

GetAttribute Generics way.

Vadim — Wed, 26 Mar 2008 19:51:06 +0000

As developers we often need to work with Xml. In my case I found myself writing code like this one:

public void Main()
{
  string name;
  bool required;
  XmlDocument _xmlDoc = new XmlDocument();
  _xmlDoc.LoadXml("");
  if (_xmlDoc.DocumentElement.HasAttribute("name"))
    name = _xmlDoc.DocumentElement.GetAttribute("name");
  if (_xmlDoc.DocumentElement.HasAttribute("required"))
    required = Convert.ToBoolean(_xmlDoc.DocumentElement.GetAttribute("required"));
}

I hated the fact that I have to for every attribute use two lines in my Main function. Below you can see refactored code.

Note: You will need to pass XmlNamespaceManager if you’re using namespaces.

public void Main()
{
  XmlDocument _xmlDoc = new XmlDocument();
  _xmlDoc.LoadXml("");
  string name = GetAttribute<string>(_xmlDoc.DocumentElement, "name");
  bool required = GetAttribute<bool>(_xmlDoc.DocumentElement, "required");
}

private T GetAttribute(XmlElement columnElement, string attributeName)
  where T : IConvertible
{
  if (columnElement.HasAttribute(attributeName))
    return (T) Convert.ChangeType(columnElement.GetAttribute(attributeName), typeof (T));
  return default(T);
}

I hope you’ll find it useful.

Vadim's Weblog » Generics

foreach with Generic Dictionary

GetAttribute Generics way.