How to get a random number from range in dart?
DartDart Problem Overview
How does one get a random number within a range similar to c# Random.Next(int min, int max);
Dart Solutions
Solution 1 - Dart
import 'dart:math';
final _random = new Random();
/**
* Generates a positive random integer uniformly distributed on the range
* from [min], inclusive, to [max], exclusive.
*/
int next(int min, int max) => min + _random.nextInt(max - min);
Solution 2 - Dart
Range can be found with a simple formula as follows
Random rnd;
int min = 5;
int max = 10;
rnd = new Random();
r = min + rnd.nextInt(max - min);
print("$r is in the range of $min and $max");
Solution 3 - Dart
You can achieve it via Random
class object random.nextInt(max)
. The nextInt()
method requires a max limit. The random number starts from 0
and the max limit itself is exclusive.
import 'dart:math';
Random random = new Random();
int randomNumber = random.nextInt(100); // from 0 upto 99 included
If you want to add the min limit, add the min limit to the result
int randomNumber = random.nextInt(90) + 10; // from 10 upto 99 included
Solution 4 - Dart
This is really late, but this for anyone who still has the question.
The easiest way to get a random number between a min and a max is the following :
import 'dart:math';
int max = 10;
int randomNumber = Random().nextInt(max) + 1;
The math module in dart has a function called nextInt. This will return an integer from 0 (including 0 ) to max - 1 ( exluding max ). I want a number 1 to 10, hence I add 1 to the nextInt result.
Solution 5 - Dart
It can be achieved exactly as you intended by creating extension on int
to get random int value. For example:
import 'dart:math';
import 'package:flutter/foundation.dart';
extension RandomInt on int {
static int generate({int min = 0, @required int max}) {
final _random = Random();
return min + _random.nextInt(max - min);
}
}
And you can use this in your code like so:
List<int> rands = [];
for (int j = 0; j < 19; j++) {
rands.add(RandomInt.generate(max: 50));
}
Note that static extension methods can't be called on type itself (e.g. int.generate(min:10, max:20)
), but instead you have to use extension name itself, in this example RandomInt
. For detailed discussion, read here.
Solution 6 - Dart
Generates a random integer uniformly distributed in the range from [min] to [max], both inclusive.
int nextInt(int min, int max) => min + _random.nextInt((max + 1) - min);
Solution 7 - Dart
import 'dart:math';
Random rnd = new Random();
// Define min and max value
int min = 1, max = 10;
//Getting range
int num = min + rnd.nextInt(max - min);
print("$num is in the range of $min and $max");
Solution 8 - Dart
To generate a random double within a range, multiply a random int with a random double.
import 'dart:math';
Random random = new Random();
int min = 1, max = 10;
double num = (min + random.nextInt(max - min)) * random.nextDouble();
Solution 9 - Dart
A simpler way of doing this is to use the nextInt method within Random:
// Random 50 to 100:
int min = 50;
int max = 100;
int selection = min + (Random(1).nextInt(max-min));
https://api.dartlang.org/stable/2.0.0/dart-math/Random-class.html