## Prime number program in C++

Today we shall learn how to write a program to find a number is Prime number or not.Before we start writing a program we should learn the basic definition.A number is said to be prime number if”It is divisible by one and itself only”.Therefore while deciding a prime number we should about the factors of the given number.

To find the factors of the given number we should divide the number.If the remainder is 0 then number is divisible and it is said to be the factor of the given number.Here we shall use the modulous operator(%) to find the remainder.Let us write the code:

```#include<iostream.h>
#include<conio.h>
class prime_number
{
public:
int n;
void calculating();
};
void prime_number :: calculating()
{

int flag=0,count=0;
for(int i=2;i<n;i++)
{
count=0;
if(n%i==0)
{
count++;
flag++;
}
if(count !=0)
cout<<"\nGiven number is divisible by"<<i;
}
if(flag ==0)
cout<<"\n******Given number "<<n<<" is a prime number*******";
else
cout<<"\n********There fore given number "<<n<<" is not a prime number*********";
}
void main()
{
clrscr();
prime_number ob;
cout<<"Enter the number to check for prime number:";
cin>>ob.n;
ob.calculating();
getch();
}```

Output: