Question

So at the moment, I have a number represented by counter. The number is incremental and continues to change. My goal is to add commas every 3 digits to make the number more readable in my app. The only issue that I am running into is that

String number = counter.replaceAllMapped(new RegExp(r'(\d{1,3})(?=(\d{3})+(?!\d))'), 
                                            (Match m) => '${m[1]},');

refuses to take the integer counter as an int. How do I convert int counter into String middle before running it through

String number = middle.replaceAllMapped(new RegExp(r'(\d{1,3})(?=(\d{3})+(?!\d))'), 
                                       (Match m) => '${m[1]},');

My goal is this:

counter = 1000;

middle = "1000";

number = "1,000";

Will my current solution even work? If not, how do I change my code to meet my goal?

Update: Here is my code:

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => new _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int counter = 0;

  void _incrementCounter() {
    setState(() {
      if (counter > 99999999) {
        //WinLandingPage();
      } else if (counter >= 99000000) {
        counter++;
      } else if (counter > 990000) {
        counter += 1000000;
      } else if (counter > 9900) {
        counter += 10000;
      } else if (counter > 99) {
        counter += 100;
      } else counter++;
    });
  }

    //BELOW is where the format is taking place, and I have no idea how to 
    //get this part working. This is my broken attempt. 

  var f = new NumberFormat("#,###,###,###", "en_US");
  var number = f.format(counter);

    //What am I doing wrong here?

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar (
        title: new Text(widget.title),
      ),
      body: new Center(
        child: new Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            new Text(
              'Try to get $number to 100,000,000.',
            ),
            new Text(
              '$number',
              style: Theme.of(context).textTheme.display1,
            ),
          ],
        ),
      ),
      floatingActionButton: new FloatingActionButton(
        onPressed: _incrementCounter,
        backgroundColor: Colors.pinkAccent,
        tooltip: 'Increment',
        child: new Icon(Icons.add),
      ),
    );
  }
}

What am I doing wrong in this piece of code? I am super unfamiliar with Dart, but I am doing my best to figure it out from trial, error, and support from you guys.

Answer 1

您可以使用NumberFormat包中的intl来执行此操作

README.md的一个例子

var f = new NumberFormat("###.0#", "en_US");
  print(f.format(12.345));
    ==> 12.34

你的例子可能是

var f = new NumberFormat("#,###", "en_US");
  print(f.format(1000));
    ==> 1,000

How do I convert an int into a string in Dart?

1 个答案: