Please modified the program

As I said in my previous post, you need to have a 'return' statement there to force the application to close.

If you didn't include it, then the while statement would simply continue.

Instead of 'return', you could also use 'break' which would exit the while statement and allow the Main method (and hence the application itself) to terminate 'normally'.

Thank you very much for your explanation. Please explain what is the purpose of having return within the if block.

if (!HourlyPayRate(out payRate)) // non-numeric input entered
{
        Console.WriteLine("Program Ends");
        Console.ReadKey();
        return;
}

The HourlyPayRate method returns a bool and also (in effect) returns a double in the HPayRate 'out' parameter. This is because a value must always be assigned to an out parameter before the method returns otherwise the compiler will complain.

If the user enters a valid double, the method returns true and the actual double value in the out parameter.

If the user fails to enter a valid double, the method returns false and a value of 0 in the out parameter.

This behaviour is simply reflecting the behaviour of the Double.TryParse method:

http://msdn.microsoft.com/en-us/library/system.double.tryparse.aspx 

So if the method returns false, the return statement is called to exit the Main method and hence the program itself - otherwise the while statement would continue.

This is exactly satisfies my requirement. Thank you very much for your help.

(1) I wish to learn about following code, please give me addresses of the relevant website

if(!HourlyPayRate(out payRate)) // non-numeric input entered

(2) What is the reason to have return within the if block.

if (!HourlyPayRate(out payRate)) // non-numeric input entered
{
 Console.WriteLine("Program Ends");
 Console.ReadKey();
 return;
}

This program ends if input is ACCEPTABLE value. Following output shows that. If it is possible to modify the program if input is not a numeric value only program ends, otherwise program will continue. (example: Hourly Pay Rate is $afdasf)

/*
Hourly Pay Rate is $80
$80.00 Not Acceptable

Hourly Pay Rate is $5
$5.00 Not Acceptable

Hourly Pay Rate is $44
$44.00 Acceptable
Program Ends
*/

Sure, to avoid repeating the same code, just change the program to this: 

using System;

namespace CheckLowRate
{
   class EnsureValidPayRate
   {
      static void Main(string[] args)
      {        
         double payRate;
 
         while(true)
         {
           if(!HourlyPayRate(out payRate)) break; // non-numeric unput entered

           if (49.99 >= payRate && payRate >= 5.65)
           {
              Console.WriteLine("{0} Acceptable", payRate.ToString("C"));
              break;
           }

           Console.WriteLine("{0} Not Acceptable", payRate.ToString("C"));
         }

         Console.WriteLine("Program Ends");
         Console.ReadKey();
      }

      public static bool HourlyPayRate(out double HPayRate)
      {
         Console.Write("\nHourly Pay Rate is $");
         bool isValid = Double.TryParse(Console.ReadLine(), out HPayRate);
         return isValid;
      }
   }
}

Thank you very much for your help.

Whether it is possible to modify, so that output will be as follows:

/*
Hourly Pay Rate is $5
$5.00 Not Acceptable

Hourly Pay Rate is $12
$12.00 Acceptable

Hourly Pay Rate is $4
$4.00 Not Acceptable

Hourly Pay Rate is $11
$11.00 Acceptable

Hourly Pay Rate is $afdasf
Program Ends
*/

Try this: