19) Loops

♣    Whenever we want to execute a single statement or a block of statements multiple times based on some condition then we can go for loops

♣    In C#.Net we can implement loops in 4 ways

                 1. For Loop

                 2. While Loop

                 3. Do While Loop

                 4. For Each Loop

For Loop :

Syntax :

for(<initialization>; <condition>;<++ or –>)
{
          Statement 1;
          Statement 2;
}

♣    Write a Program to Print 1 to 10 numbers by using For loop

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ForLoop
{
    class Program
    {
        static void Main(string[] args)
        {
            /*eexample of for loop*/
            for (int i = 1; i <= 10; i++)
            {
                Console.WriteLine(i);
            }
            Console.ReadLine();
        }
    }
}

Output :

Note : Executing For Block once is called as one iteration, the no of iterations are deciding  by condition

While Loop :

Syntax :

While (<condition>)
{
             statement 1;
             statement 2;
             ++ or --
}

♣    Write a Program to Print 1 to 10 Numbers by using While loop

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace WhileLoop
{
    class Program
    {
        static void Main(string[] args)
        {
            /*example while loop print 12345678910*/
            int i = 1;
            while (i <= 10)
            {
                Console.Write(i);
                i++;
            }
            Console.ReadLine();
        }
    }
}

Output :

Do While :

Syntax :

Do
{
     statement 1;
     statement 2;
     + + or - -;
}
while (<condition>)

♣    Even though condition is false first time but still do while loop will execute one iteration

♣    Whenever we want to execute at least one iteration irrespective of condition then we have to implement Do-While.

♣    In FOR and While Loop pre condition checking but in do while loop post condition checking.

♣    Example to Print 1 to 10 Numbers by using Do-While

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace DoWhileLoop
{
    class Program
    {
        static void Main(string[] args)
        {
            /* do while loop to print 1,2,3,4,5,6,7,8,9,10.*/
            int i = 1;
            do
            {
                if (i < 10)
                    Console.Write(i + ",");
                else
                    Console.Write(i + ".");
                i++;
            } while (i <= 10);
            Console.ReadLine();
        }
    }
}

Output :