How can I input this C++ code in Dart [closed] - c++

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I have to make this C++ code in Dart, but I find it really difficult. I tryed watching Darts video and searching on the web, but with no success.Could someone be able to give me a hand?
This is the code:
#include <iostream>
using namespace std;
int main()
{
int n;
cin >> n;
if (n < 0) return 1;
int sum = 0;
int i = 0;
while (i <= n) sum += i*i;
cout << sum;
return 0;
}

Answer 1

something like
library x;
import 'dart:io';
void main(List<String> args) {
int n;
print('input a number');
String input = stdin.readLineSync();
n = int.parse(input);
print('n: $n');
if(n < 0) {
exit(1);
}
int sum = 0;
int i = 0;
while(i <= n) {
print(sum);
sum += i * i;
}
print(sum);
}
But don't expect to much.
When reaching the while loop sum and i are 0.
This way you have produced a nice endless loop to busy your computer ;-)

Answer 2

You could do the calculation bit (sum of squares of all numbers from 1 to n inclusive) with a recursive function like:
int recur(int n) => (n > 0) ? (n * n) + recur(n - 1) : 0;
Then it's a simple matter of figuring out how to enter n and output recur(n). That can be done with stdin.readLineSync and print. That would be along the following lines:
int recur(int n) => (n > 0) ? (n * n) + recur(n - 1) : 0;
void main( List<String> args ) {
int inNum;
String input = stdin.readLineSync();
inNum = int.parse( input );
if (inNum < 0) {
exit( 1 );
}
print( recur( sum ) );
}
Just be careful with large input values, I'm not sure whether Dart is smart enough to do tail end recursion optimisation. If not, stack space may be an issue.