编辑代码

Function makeAdder(num addBy) {
  return (num i) => addBy + i;
}

void main() {
  
  int num;
  
  var one = '1';
  
  assert( num != null );
  
  print( int.parse(one) == 1 );
  print(1.toString());
  print(1.23423423234324.toStringAsFixed(2));

  print((3 << 1) == 6);


  var list = [1, 2, 3];
  print(list.length == 3);
  print(list[1] == 2);

  list[1] = 1;
  print(list[1] == 1);


var names = <String>{};
var halogens = {'fluorine', 'chlorine', 'bromine', 'iodine', 'astatine'};
//集合操作，加入一个元素或者集合
var elements = <String>{};
elements.add('fluoriness');
elements.addAll(halogens);

print(elements);

var nobleGases = Map();
nobleGases[2] = 'helium';
nobleGases[10] = 'neon';
nobleGases[18] = 'argon';

bool isNoble(int atomicNumber) => nobleGases[atomicNumber] != null;

print( isNoble(2) );

var add2 = makeAdder(2);
print( add2(1) );
}