# Rust Sum primes

VonRickroll

3,519 views

The goal today is to write a function that returns the sum of all prime numbers up to a limit. We will do this in two steps: first we're going to write an `isPrime`

function that checks wether or not a number is prime, and then the actual `sumPrimes`

function.

## Check if a number is prime

Write an `isPrime`

function that takes an `i32`

number as parameter and returns true if this number is prime, false if it isn't.

*Reminder:* A prime number:

- Can only be divided by
`1`

and itself - Is greater than
`1`

Write the isPrime function

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pub fn is_prime(number: i32) -> bool {

println!("The number is {}", number);

return true;

// For demo purposes:

/*

for i in 2..(number / 2 + 1) {

if number % i == 0 {

return false;

}

}

return number > 1;

*/

}

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## Sum all primes

Write a `sumPrimes`

function to sum all prime numbers up to the parameter `limit`

*included*. Copy you `isPrime`

function from the last assignment to make use of it

Write the sumPrimes function

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pub fn is_prime(number: i32) -> bool {

println!("The number is {}", number);

return true;

// For demo purposes:

/*

for i in 2..(number / 2 + 1) {

if number % i == 0 {

return false;

}

}

return number > 1;

*/

}

pub fn sum_prime(limit: i32) -> i32 {

println!("The limit is {}", limit);

return 0;

// For demo purposes:

/*

let mut sum = 0;

for x in 2..(limit+1) {

if is_prime(x) {

sum += x;

}

}

return sum;

*/

}

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