If I input a number, how can I output all the numbers to that input number and check if it is prime?

Question

I also want to know how can I (for every number) output the numbers that evenly divide?

Answer 1

#include<iostream>
int main() {
int user_input, x;
std::cout << "This program will check for prime numbers\n";
std::cout << "Please enter an integer upper bound: ";
std:: cin >> user_input;
//this for loop goes through each number up to the user input upper boundary
for (int i = 2; i < user_input; i++){// i starts at 2 because the numbers 1 and 2 are by default prime numbers.
x = 0;//a variable to check if a number is prime. If it gets set to 1 the number is not prime.
for (int j = 2; j < i; j++){//this loop divides the number by 2 up to itself and if the remainder is 0 sets x = 1.
if (i%j == 0){
x = 1;
break;
}
}
if (x == 0){//if the x = 1 flag is never set the number is prime.
std::cout << i << " is a prime number\n";
}
}
return 0;
}
Edit & Run

edit.. guess i could add some comments to explain it sec.