DS-LAB(PRIME NO.) EXPERIMENT-5

Algorithm

Input Any integer number (up to 32767)
Output Is it a prime number or Not
Complexity O(n)
Prime(num)
1 Set i=2
2 while i<=num/2
3      if  num mod i = 0
4          print "Not a Prime number" and exit;
5     i=i+1
6 if (i==(num/2)+1)
7 Print "Prime number"

FLOWCHART

C++ program to Check Prime Number

/* C++ program to check whether a number is prime or not. */

#include <iostream>
using namespace std;

int main()
{
  int n, i, flag=0;
  cout << "Enter a positive integer: ";
  cin >> n;
  for(i=2;i<=n/2;++i)
  {
      if(n%i==0)
      {
          flag=1;
          break;
      }
  }
  if (flag==0)
      cout << "This is a prime number";
  else
      cout << "This is not a prime number";
  return 0;
}