.net - Why we need Properties in C#

Question

Can you tell me what is the exact usage of properties in C# i mean practical explanation

in our project we are using properties like

/// <summary>
/// column order
/// </summary>
protected int m_order;

/// <summary>
/// Get/Set column order
/// </summary>
public int Order
{
   get { return m_order; }
   set { m_order = value; }
}

/// <summary>
/// constructor
/// </summary>
/// <param name="name">column name</param>
/// <param name="width">column width</param>
/// <param name="order">column order</param>
public ViewColumn(string name, int width, int order)
{
   //
   // TODO: Add constructor logic here
   //
   m_name = name;
   m_width = width;
   m_order = order;
}  


/// <summary>
/// returns the column name, width, and order in list view.
/// </summary>
/// <returns>string represent of the ViewColumn object</returns>
public override string ToString()
{
  return (string.Format("column name = {0}, width = {1}, order = {2}.", 
        m_name, m_width, m_order));
}

/// <summary>
/// Do a comparison of 2 ViewColumn object to see if they're identical.
/// </summary>
/// <param name="vc">ViewColumn object for comparison</param>
/// <returns>True if the objects are identical, False otherwise.</returns>
public override bool Equals(object obj)
{
   ViewColumn vc = (ViewColumn)obj;
   if(m_name == vc.Name &&
        m_width == vc.Width &&
        m_order == vc.Order)
      return true;
   else
      return false;
}

Answer 1

Short answer: Encapsulation

Long answer: Properties are very versitile. It allows you to choose how you want to expose your data to outside objects. You can inject some amount of data validation when setting values. It also aliviates the headache of getX() and setX() methods seen in the likes of Java, etc.