Question

From another website:

Printing all the prime numbers between 0 and 100 (this is a tricky one!)

How can I do this?

Answer 1

I'm assuming you want a specific example, although I can also do theory. First, you create an empty list of prime numbers. Then, you run through numbers 2 to 100, and each time you get to a number that doesn't have any factors in the list of primes, you add it to the list of primes. Then you print out the list. In python:

primes = []

def isPrime(num):
for primeNum in primes:
if(num % primeNum == 0):
return False
return True

for i in range(2, 100):
if(isPrime(i)):
primes.append(i)

print(primes)

Answer 2

It helps but, I need in javascript. My idea it's to check every number if is prime. Another solution?

Answer 3

Here you go

// Check if a number is prime.
function isPrime(N)
{
for (var i = 2; i < N; i++)
{
if (N % i == 0 && i != N) // Checks if N is prime or not.
return false;
}
return true;
}
// Gets all primes from inclusive 'startN' to inclusive 'endN'.
function getAllPrimesBetween(startN, endN)
{
var primes = []; // Array holding primes.
for (var N = startN; N <= endN; N++) // For loop.
{
if(isPrime(N)) // Checking if N is prime and eventually adding it to array.
primes.push(N); // Adds N to array.
}
return primes;
}

// Usage sample.
// Gets an array of primes from 2 to 100.
getAllPrimesBetween(2,100);
// [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]