String x = '5 + 6'
How do I evaluate the string above so that it produces result. 5 + 6 equals 11. How do I get that result from the above string?
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can you help me find that, any clue to the source I should look into? @julemand101user13427040– user134270402020-04-30 13:31:28 +00:00Commented Apr 30, 2020 at 13:31
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I have added an answer with example of using two different packages.julemand101– julemand1012020-04-30 13:43:13 +00:00Commented Apr 30, 2020 at 13:43
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2 Answers
Alternative you can also make use of the math_expressions package:
import 'package:math_expressions/math_expressions.dart';
void main() {
String x = '5 + 6';
print(solve(x)); // 11
}
int solve(String expr) =>
(Parser().parse(expr).evaluate(EvaluationType.REAL, ContextModel()) as double)
.toInt();
Or use expressions which seems to be more simple to use but have fewer features:
import 'package:expressions/expressions.dart';
void main() {
String x = '5 + 6';
print(solve(x)); // 11
}
int solve(String expr) =>
const ExpressionEvaluator().eval(Expression.parse(expr), null) as int;
Both packages should work with Flutter.
Comments
import 'dart:isolate';
void main() async {
var sumString = '5 + 6';
final uri = Uri.dataFromString(
'''
import "dart:isolate";
void main(_, SendPort port) {
port.send($sumString);
}
''',
mimeType: 'application/dart',
);
final port = ReceivePort();
await Isolate.spawnUri(uri, [], port.sendPort);
final int response = await port.first;
print(response);
}
This is based on How do I execute Dynamically (like Eval) in Dart?
Also note:
Note that you can only do this in JIT mode, which means that the only place you might benefit from it is Dart VM command line apps / package:build scripts. It will not work in Flutter release builds.
2 Comments
Lesiak
Check my answer: it will NOT work in flutter release build.