Write a C++ Program to Check a number is Prime or not

By | 25.12.2016

Check a number is Prime or not


Write a C++ Program to Check given number is Prime number or not. Here’s simple C++ Program to Check given number is Prime number or not in C++ Programming Language.


A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. It means a prime number is only divisible by 1 and itself, and it start from 2. The smallest prime number is 2

Here is source code of the C++ Program to Check given number is Prime number or not. The C++ program is successfully compiled and run(on Codeblocks) on a Windows system. The program output is also shown in below.


SOURCE CODE : :


/*  C++ Program to Check given number is Prime number or not  */

#include<iostream>
using namespace std;

int main()
{
  int i,n;

  cout<<"Enter any positive number :: ";
  cin>>n;

  if(n==1)
  {
    cout<<"\nSmallest prime number is :: 2";
  }

  for(i=2;i<n;i++)
  {
      if(n%i==0)
      {
          cout<<"\nThe Entered Number [ "<<n<<" ] is NOT a prime number.\n";
          break;
      }
  }

 if(n==i)
 {
    cout<<"\nThe Entered Number [ "<<n<<" ] is a prime number.\n";
 }

  return 0;
}

Output : :


/*  C++ Program to Check given number is Prime number or not  */

Enter any positive number :: 97

The Entered Number [ 97 ] is a prime number.

Process returned 0

Above is the source code for C++ Program to Check given number is Prime number or not which is successfully compiled and run on Windows System.The Output of the program is shown above .

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ahmedseid

if i=10 and n=10 i,e n=i, is n(10)prime?

codezclub  Post author

but it’s not possible,Since we create a condition ::
if(n%i==0)

then break;

Correct code

#include <iostream>

using namespace std;

int n;
bool isnum = true;

int main()
{
cout << “enter the number ” << endl;
cin >> n;
if (n == 0 || n == 1)
{
  isnum = false;
}
else{
  for (int i=2; i <= n/2; ++i) {
    if (n%i == 0) {
      isnum = false;
      break;
    }
  }
}
if (isnum) {
  cout << “number is prime ” << endl;
   
}
else { 
  cout << “number is not prime ” << endl;
}

  return 0;
}

Alexis Siobhan Douglas

#include <iostream>
#include <cmath>
using namespace std;

int main()
{
cout << “Enter a number:: “;
int num;
cin >> num;

if (num > 0) {
if ((num % 2 == 0) || (num % 3 == 0))
cout << “Not a Prime Number”;
else if ((num % 2 != 0) || (num % 3 != 0))
cout << ” Is a prime number”;
else
cout << “Invalid”;

}

return 0;
  }

// Prime numbers: 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 61 67 71 73 79 83 89 97

Ajay Waghmare

Great I like your website. You solved all the problems of a college student now they will not build their own algorithm and will fail in interview.