IFormattable example

gistfile1.cs

public class User : IFormattable
{
	private int _age;
	private string _name;
	
	/// <summary>
	/// Gets/sets the Name.
	/// </summary>
	public string Name
	{
		get { return _name; }
		set { _name = value; }
	}

	/// <summary>
	/// Gets/sets the Age.
	/// </summary>
	public int Age
	{
		get { return _age; }
		set { _age = value; }
	}

	/// <summary>
	/// Object.ToString() implementation
	/// </summary>
	public override string ToString()
	{
		return string.Format("'{0}', age {1}", Name, Age);
	}

	/// <summary>
	/// Just a format string, functionality you find in DateTime.Now.ToString()
	/// </summary>
	public string ToString(string format)
	{
		return ToString(format, null);
	}

	/// <summary>
	/// IFormattable.ToString() implementation
	/// </summary>
	public string ToString(string format, IFormatProvider formatProvider)
	{
		// Default format
		if (string.IsNullOrEmpty(format) || format == "G")
			return string.Format("'{0}', age {1}", Name, Age);
		if (format == "name")
			return Name;
		else if (format == "age")
			return Age.ToString();
		else
		{
			// The IFormattable example shows branching based on the format. This is fine if the class
			// is being used with composite formatting, however to support the DateTime.Now.ToString("xxx")
			// style formatting, we need the below.
			string result = format;
			result = result.Replace("name", Name);
			result = result.Replace("age", Age.ToString());
			return result;
		}
	}
}