Flutter - Write results in CMD

Question

I want to have a Windows executable created with Flutter to be able to accept command arguments and print the result inside my CMD when I execute it like this :

commandtest.exe --type=csv

I wrote this code :

import 'dart:io';

import 'package:args/args.dart';

void main(List<String> args) {
  var parser = ArgParser()..addOption("type", abbr: 't', defaultsTo: 'default');

  try {
    final ArgResults argResults = parser.parse(args);

    final String type = argResults['type'] as String;

    stdout.writeln('Type: $type'); // print() doesn't work either
    exit(0);
  } on Exception catch (e) {
    stderr.writeln("error on parsing args : $e");
    exit(1);
  }
}

Here's my expected behavior, in my CMD :

path/to/executable> mycommand.exe --type=csv
Type: csv

path/to/executable>

But for now, nothing works and my CMD is empty when i run my command :

path/to/executable> mycommand.exe --type=csv

path/to/executable>

However, I know it works because when I try my command like this :

mycommand.exe --type=csv > output.txt

the output.txt file is created and my result is correctly pushed inside.

I don't see where's the problem. Help please ?

Answer 1

The behaviour that you are showing occurs when you run a Windows GUI app from cmd: These do not print anything to the cmd output. They still have a stdout which you can redirect in the way that you showed - but they won't print it to the console output.

You probably used flutter create commandtest to create your application. This way, you create a cmake project that builds an app as a windows gui application.

Instead, use dart create commandtest to create a pure dart app. Copy your code to bin\commandtest.dart. Create the exe with dart compile exe bin\commandtest.dart.