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C++ program to display prime numbers

Input the value of N and then print the primer numbers between 1 to N using C++ program.
[Last updated : February 28, 2023]

C++ - Printing prime numbers between 1 to N

In this program, we will read the value of N (range of the numbers) and print the all prime numbers from 2 to N.

To check prime numbers, we are creating a user defined function isPrime() that will take an integer number and return 1 if number is prime and 0 if number is not prime.

Program to display prime numbers in C++

#include <iostream>
using namespace std;

//function to check prime numbers
int isPrime(int num);

int main()
{
    int i;
    int n; //to store, maximum range

    cout << "Enter maximum range (n): ";
    cin >> n;

    //print prime numbers from 2 to n
    cout << "Prime numbers:" << endl;
    for (i = 2; i < n; i++) {
        if (isPrime(i))
            cout << i << " ";
    }
    cout << endl;

    return 0;
}

//function definition
int isPrime(int num)
{
    int cnt;
    int prime = 1;

    for (cnt = 2; cnt <= (num / 2); cnt++) {
        if (num % cnt == 0) {
            prime = 0;
            break;
        }
    }
    return prime;
}

Output

Enter maximum range (n): 100
Prime numbers:
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97

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