How do I read console input / stdin in Dart?

Question

How do I read console input from stdin in Dart?

Is there a scanf in Dart?

Answer 1

With M3 dart classes like StringInputStream are replaced with Stream, try this:

import 'dart:io';
import 'dart:async';

void main() {
  print("Please, enter a line \n");
  Stream cmdLine = stdin
      .transform(new StringDecoder())
      .transform(new LineTransformer());

  StreamSubscription cmdSubscription = cmdLine.listen(
    (line) => print('Entered line: $line '),
    onDone: () => print(' finished'),
    onError: (e) => /* Error on input. */);


}

Answer 2

The readLineSync() method of stdin allows to capture a String from the console:

import 'dart:io';

main() {
    print('1 + 1 = ...');
    var line = stdin.readLineSync(encoding: Encoding.getByName('utf-8'));
    print(line.trim() == '2' ? 'Yup!' : 'Nope :(');
}

Answer 3

import 'dart:io';

void main(){
  stdout.write("Enter your name : ");
  var name = stdin.readLineSync();
  stdout.write(name);
}

Output

Enter your name : Jay
Jay

By default readLineSync() takes input as string. But If you want integer input then you have to use parse() or tryparse().

Answer 4

The following should be the most up to date dart code to read input from stdin.

import 'dart:async';
import 'dart:io';
import 'dart:convert';

void main() {
  readLine().listen(processLine);
}

Stream<String> readLine() => stdin
    .transform(utf8.decoder)
    .transform(const LineSplitter());

void processLine(String line) {
  print(line);
}