Category: Programming

Math.Round has been improved in C#.
Consider the below piece of code:

Console.WriteLine(Math.Round(10.4)); // Rounds to 10.0
Console.WriteLine(Math.Round(10.7)); // Rounds to 11.0
Console.WriteLine(Math.Round(10.5)); // Rounds to 10.0

There is nothing surprising about the first two statements.
In the third statement however, 10.5 is rounded to 10 not 11. C# provides for a way to specify how the middle point has to be treated.
A enumeration ‘MidpointRounding’ that defines how mid points are treated.

Console.WriteLine(Math.Round(10.5, MidpointRounding.AwayFromZero)); // Rounds to 11.
Console.WriteLine(Math.Round(10.5, MidpointRounding.ToEven)); // Rounds to 10.
Console.WriteLine(Math.Round(11.5)); //Rounds to 11.
Console.WriteLine(Math.Round(11.5, MidpointRounding.AwayFromZero)); // Rounds to 12.
Console.WriteLine(Math.Round(11.5, MidpointRounding.ToEven)); // Rounds to 12.

‘AwayFromZero’ – Rounds the number to the next highest value.
‘ToEven’ – Rounds the number to Even number.

So for a odd fraction, the default round will round it to the lesser number and any of the above overloads will take it to the Next number.

C# 2008 allows for creating implicit variables using the ‘var’ keyword. But the usage of ‘var’ cannot be truly justified for just declaring a ‘int’ or ‘string’ in code as shown in example below.

var intNum = 5;

Console.WriteLine("intNum is a: {0}", intNum.GetType().Name);
Console.WriteLine("intNum is defined in: {0}", intNum.GetType().Namespace);

The output of the above program is

intNum is a: Int32
intNum is defined in: System

Here instead of using int in the declaration, we have used ‘var’ keyword. There is no difference between using ‘int’ or ‘var’ in the above example.
The real usage of ‘var’ comes in LINQ. Consider the following code.

int[] numbers = { 10, 20, 30, 40, 8, 7, 6, 2 };
var resultSet = from i in numbers where i < 10 select i;

foreach (var i in resultSet)
{
Console.Write("{0}", i);
}

Console.WriteLine("resultSet is a: {0}", resultSet.GetType().Name);
Console.WriteLine("resultSet is defined in: {0}", resultSet.GetType().Namespace);

Here resultSet is declared as a ‘var’. From the code, we understand that anytime, the resultSet will be an array of integers. But ‘resultSet.GetType().Name’ gives a surprising result.

resultSet is a: d__0`1
resultSet is defined in: System.Linq

So ‘var’ has its best usage in LINQ. So why use it in a normal program when the datatype can be used in itself.

Here is a tip shared by Kannan, a colleague of mine on how to avoid flickering when rendering controls dynamically in a Windows Application.

Enable double buffering, so that the flickering does not happen.

Add the following after the ‘InitializeComponent’ method.

      SetStyle(ControlStyles.UserPaint, true);
      SetStyle(ControlStyles.AllPaintingInWmPaint, true);
      SetStyle(ControlStyles.DoubleBuffer, true);

That’s it.