C++ Exercises: Check whether a number is prime or not

C++ For Loop: Exercise-5 with Solution

Write a program in C++ to check whether a number is prime or not.

Pictorial Presentation:

Sample Solution :-

C++ Code :

#include <iostream>
using namespace std;
int main()
{
    int num1, ctr = 0;
    cout << "\n\n Check whether a number is prime or not:\n";
	cout << "--------------------------------------------\n";
	cout << " Input a number to check prime or not: ";
	cin>> num1;	
    for (int a = 1; a <= num1; a++) 
    {
        if (num1 % a == 0) 
        {
            ctr++;
        }
    }
    if (ctr == 2) 
    {
        cout << " The entered number is a prime number. \n";
    }
    else {
        cout << " The number you entered is not a prime number. \n";
    }
}

Sample Output:

 Check whether a number is prime or not:                               
--------------------------------------------                           
 Input a number to check prime or not: 13                              
 The entered number is a prime number. 

Flowchart:

C++ Code Editor:

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