Loop Statement in C# , Control Structure in C#, For Loop, While Loop and Do While Loop Concept in C#

Loop Statement in C#, Control Structure in C#, For Loop, While Loop and Do While Loop Concept in C#:-

Loop is used to print or enumerate large statements of data using a single repeatable block, Loop is also called an iterative statement because it will repeat the data according to condition.


Type of Loop:-

1)Entry Control Loop:-

First check condition then execute loop statements hence it is called entry control.

1.1)  While Loop:-

          Syntax of While Loop:-

               init;
               while(condition)
               {
                          Statement;
                          Increment;

               }



Now I am discussing one simple program of while loop, suppose I want to display a range of elements from1 to 100?

Solution:-

int i=1;

while(i<=100)

{

      Console.WriteLine(i);

      i++;

}

suppose I want to display a range of elements from100 to 1?

Solution:-

int i=100;

while(i>=1)

{

      Console.WriteLine(i);

      i--;

}

Write a program to calculate a table of any number using a complete expression?

class CalculateTable

    {

        static void Main()

        {

            int num,i;

            Console.WriteLine("Enter number to print table");

            num = int.Parse(Console.ReadLine());

            i = 1;

            while (i <= 10)

            {

                Console.WriteLine("{0}*{1}={2}",num,i,num * i);

                i++;

            }

            Console.ReadKey();

        

        }

    }

Infinite While Loop in C#:-

Infinite loop means, loop without any finite condition for example if we pass true under while loop, then it will automatically be converted into the infinite while loop.

When we want to create an infinite loop in C# then we prefer while loop Otherwise we will use for Loop




Syntax of Infinite While Loop:-

while(true)

{

        Statements;

}

Example of Infinite While Loop:-

class WhileExample
    {
        public static void Main()
        {
            int i = 1;
            while (true)
            {
                Console.WriteLine(i);
                i++;
                if (i == 10)
                    break;
            }
            Console.ReadKey();
        }
    }



Another Example of Infinite While Loop:-

 class WhileExample

    {

        static void Main()

        {

            bool flag = true;

            int x = 0;

            while (flag)

            {

                Console.WriteLine("hello"+x);

                x++;

                if (x > 10)

                {

                    flag = false;

                }

            }

            Console.ReadKey();

        }

    }

1.2)   For Loop:- 

This Loop will contain all statements (initialization, condition, and iteration) using a single statement. that's why for loop provides a simple syntax structure as compared to the while loop. we always prefer for  loop to solve range-based problems.

Syntax of for loop:-

      

     1      2               4

for(init;condition;iteration)

    {

           3
          Statement;
    }

WAP to check the prime number?

using System;


namespace ConsoleApplication2
{
    class CheckPrime
    {
        static void Main()
        {
            int num;
            Console.WriteLine("Enter number");
            num = int.Parse(Console.ReadLine());
            int c = 0;
            for (int i = 1; i <= num; i++)
            {
                if (num % i == 0)
                    c++;
            }
            if (c == 2)
                Console.WriteLine("Prime");
            else
                Console.WriteLine("Not Prime");
            Console.ReadKey();
        }
    }
}

WAP to check prime number without using the third variable?


class CheckPrime
    {
        static void Main()
        {
            int num,i;
            Console.WriteLine("Enter number");
            num = int.Parse(Console.ReadLine());
         
            for (i = 2; i < num; i++)
            {
                if (num % i == 0)
                {
                    Console.WriteLine("Not Prime");

                    break;
                }
            }
            if (num==i)
                Console.WriteLine("Prime");
         
             
            Console.ReadKey();
        }
    }


WAP to check prime number with complete program optimization?

class CheckPrime
    {
        static void Main()
        {
            int num,i;
            Console.WriteLine("Enter number");
            num = int.Parse(Console.ReadLine());
         
            for (i = 2; i < num/2; i++)
            {
                if (num % i == 0)
                {
                    Console.WriteLine("Not Prime");

                     break;
                }
            }
            if (num/2==i)
                Console.WriteLine("Prime");
         
             
            Console.ReadKey();
        }
    }


2) Exit Control Loop:-

First, execute the loop statement then check the condition, this loop will not use mostly on application programming.

2.1)  do--while:-   

First, execute the statement then check the condition.

Syntax of Do--While Loop:-

init;
do
{
      Statement;
      Increment;

}while(condition);


WAP to print 1 to 10 and 10 to 1 using do-while Loop?


class DoWhileExample
    {
        public static void Main()
        {
            int i = 1;
            do
            {
                if (i <= 10)
                    Console.WriteLine(i);
                else
                    Console.WriteLine(21-i);
                i++;
            } while (i <= 20);
            Console.ReadKey();
        }
    }


Q) Program to implement Fibonacci series?

using System;

// 0 1 1 2 3 5 8 13

class DowhileExample

{

    public static void Main()

     {

        int a=-1,b=1,c=0,i=1;

        do

        {

          c = a+b;

          Console.WriteLine(c);

          a=b;

          b=c;

          i=i+1;

        }while(i<=10);

     }

}

ASSIGNMENT of LOOP:-


 1)  WAP to check prime number without using a third variable?

3)  WAP to find the first, second, and third max number in pin code?

2)  WAP to display the table of each Fibonacci series digit?

0 1 1 2 3 5 8 13

WAP to check prime number with complete expression

5    5%2,5%3,5%4

WAP to print factorial with expression

5*4*3*2*1=120

4) WAP  to check that a particular digit exists in a mobile number or not and display the number of times?