4.Write a program in c language to check if a given number is a prime number or not using a while loop.

Introduction
We are writing a C program to check whether a number given by user is a prime number or not. a prime number is greater than 1 and natural number it has no positive divisor except 1 and itself. The while loop has used to check the divisibility of the given number by numbers less than itself to check if the number is prime number.
Objective
The main objective of developing this program in the C language is to test if a given number is a prime number or not using a while loop.
While loop is to be professionally used to decide whether a given number is a prime number or not. In simple word we define a prime number is a number that is only divisible by 1 and itself and not by other factors. By constructing this program our goal is to deliver a practical solution for classifying prime numbers which can be useful in several mathematical and computational applications.

Purpose
The purpose of the given program is to determine the usage of programming ideas, precisely the while loop in C language to resolve a shared mathematical problem. By examination whether a given number is prime or not we can show the logic and structure essential to implement such functionality in c programming. The program helps as a learning resources for those involved in understanding how to write code to resolve mathematical problems and recover their programming skills set.

Real Life Applications
There are vast number of application of prime number in real life.
The prime number application is in the area of cryptography and computer security.
The prime numbers are also used in RSA(Rivest-Shamir-Adleman) encryption algorithms to protect and secure sensitive information in digital transaction and communication.
Prime numbers are used in generating secure key for safe and secure ecommerce transaction, banking transaction and other applications where data is confidential.
Moreover the prime numbers are used in numerous scientific and mathematical fields such as prime factorization algorithms ,number theory and prime number sieves.

/* a program in c language to check if a given number is a prime number
or not using a while loop. */
#include <stdio.h>
int main()
{
int n, cnt= 2, flg = 0;
// Input the number
printf("\n Enter any number: ");
scanf("%d", &n);
// Check if the number is prime
while (cnt < n)
{
if (n%cnt==0)
{
flg=1;
break;
}
cnt++;
}
// display the final result
if (n==1)
{
printf("\n The number 1 is neither prime nor composite.\n");
}
else if (flg == 0)
{
printf("\n The number %d is a prime.\n", n);
}
else
{
printf("\n The number%d is not a prime ", n);
}

return 0;
}