Dart Program – Check Prime Number

In this tutorial, we shall write a function in Dart language, to check if given number N is prime number or not.

Algorithm

1. Start.
2. Read a number `N` from user.
3. Initialize `i` with 2.
4. If `i` is less than `N/i`, continue with next step, else go to step 7.
5. Check if `i` is a factor of `N`. If `i` is a factor of `N`, `N` is not prime, return false. Go to step 8.
6. If `i` is not a factor, increment `i`. Go to step 4.
7. Return `true`.
8. End.

Dart Program

In the following program, we shall write a function `isPrime()`, using the above algorithm. This function takes a number as argument, then check if the number is prime or not, and returns a boolean value. The function returns true if the number is prime, else it returns false.

main.dart

```import 'dart:io';

bool isPrime(N) {
for (var i = 2; i <= N / i; ++i) {
if (N % i == 0) {
return false;
}
}
return true;
}

void main() {
print('Enter N');
var N = int.parse(stdin.readLineSync()!);
if (isPrime(N)) {
print('\$N is a prime number.');
} else {
print('\$N is not a prime number.');
}
}```

Output#1

```Enter N
11
11 is a prime number.```

Output#2

```Enter N
25
25 is not a prime number.```

Conclusion

In this Dart Tutorial, we learned how to check if given number is Prime number or not, in Dart programming, with examples.