Csharp/CSharp Tutorial/Statement/Do While

Display the digits of an integer in reverse order with do while loop

using System; 
 
class MainClass {   
  public static void Main() { 
    int num; 
    int nextdigit; 
 
    num = 198; 
 
    Console.WriteLine("Number: " + num); 
 
    Console.Write("Number in reverse order: "); 
 
    do { 
      nextdigit = num % 10; 
      Console.Write(nextdigit); 
      num = num / 10; 
    } while(num > 0); 
 
    Console.WriteLine(); 
  }   
}

Number: 198
Number in reverse order: 891

Do while loop

A do-while loop will always execute at least once.

The general form of the do-while loop is

do {
statements;
} while(condition);

Do / while loop with a console read

using System;
using System.IO;
class MainClass
{
  public static void Main(string[] args)
  {
    string ans;
    do
    {
      Console.Write("Are you done? [yes] [no] : ");
      ans = Console.ReadLine();
    }while(ans != "yes");
  }
}

Are you done? [yes] [no] : yes

Use the do while statement to implement Newton"s method for finding the square root of a number

using System;
public class MainClass {
   public static void Main( ) {
      double epsilon   = 1.0e-9;
      double guess    = 11.0;
      double result   = 0.0;
      double value = 2;
      result = ((value / guess) + guess) / 2; 
      do {
            Console.WriteLine( "Guess Value  = {0}", guess  );
            Console.WriteLine( "Result Value = {0}", result );
            guess = result;
            result = ((value / guess) + guess) / 2;
      } while( Math.Abs(result - guess) > epsilon );
      Console.WriteLine("The approx sqrt of {0} is {1}", value, result );
    }
}

Guess Value  = 11
Result Value = 5.59090909090909
Guess Value  = 5.59090909090909
Result Value = 2.97431633407243
Guess Value  = 2.97431633407243
Result Value = 1.82336988350512
Guess Value  = 1.82336988350512
Result Value = 1.46012001740362
Guess Value  = 1.46012001740362
Result Value = 1.41493521627426
Guess Value  = 1.41493521627426
Result Value = 1.41421374640426
Guess Value  = 1.41421374640426
Result Value = 1.41421356237311
The approx sqrt of 2 is 1.41421356237309