prime numbers less than a given number c++

To find all the prime numbers less than a given number in C++, you can follow these steps:

1. Start by defining a function that takes an integer as input and returns a boolean value indicating whether it is prime or not. Let's call this function isPrime.
2. Inside the isPrime function, check if the input number is less than 2. If it is, return false because prime numbers are defined as numbers greater than 1.
3. Use a loop to iterate from 2 to the square root of the input number. For each iteration, check if the input number is divisible evenly by the current iteration number. If it is, return false because the number is not prime.
4. If the loop completes without finding any divisors, return true because the number is prime.
5. In your main program, prompt the user to enter a number.
6. Parse the user input into an integer variable.
7. Use a loop to iterate from 2 to the input number - 1. For each iteration, call the isPrime function and check if the current number is prime.
8. If the number is prime, print it out.
9. Repeat steps 7 and 8 until you iterate through all numbers from 2 to the input number - 1.

Here is an example code snippet that implements the above steps:

#include <iostream>
#include <cmath>

bool isPrime(int number) {
    if (number < 2) {
        return false;
    }

    for (int i = 2; i <= sqrt(number); i++) {
        if (number % i == 0) {
            return false;
        }
    }

    return true;
}

int main() {
    int n;
    std::cout << "Enter a number: ";
    std::cin >> n;

    for (int i = 2; i < n; i++) {
        if (isPrime(i)) {
            std::cout << i << " ";
        }
    }

    return 0;
}

This code will prompt the user to enter a number and then print out all the prime numbers less than that number.