• Its a way to achieve abstraction in c#.
• Not instantiated directly
• must contain at least one abstract method.
• used to define base class.
• contains both declaration and definition.
• contains constructor.
• it can contain static members
• contains different types of access modifiers like public, private, protected.
• performance of abstract class is fast.
• used to implement core identity of class
• a class can only use one abstract class.
• if many implementation are same kind and common behavior, then it...

static readonly Regex re = new Regex(@"\$(\w+)\$", RegexOptions.Compiled);
static void Main() {
    string input = @"Dear $name$, as of $date$ your balance is $amount$";

    var args = new Dictionary<string, string>(
        StringComparer.OrdinalIgnoreCase) {
            {"name", "Mr Smith"},
            {"date", "05 Aug 2009"},
            {"amount", ...

We can use DateTime.Now.Ticks and Guid.NewGuid().ToString() to combine together and make a unique id.

As the DateTime.Now.Ticks is added, we can find out the Date and Time in seconds at which the unique id is created.

Please see the code.

var ticks = DateTime.Now.Ticks;
var guid = Guid.NewGuid().ToString();
var uniqueSessionId = ticks.ToString() +'-'+ guid; //guid created by combining ticks and guid

var datetime = new DateTime(ticks);//for checking purpose
var datetimenow = DateTime.Now;    //b...