How to Generate Random Numbers and range of numbers in Dart or Flutter Programming with example

How to Generate Random Numbers and range of numbers in Dart or Flutter Programming with example

This tutorial shows multiple methods for generating random numbers in the Dart programming language.

A random number is a unique value generated within a specified range, ensuring unpredictability for various requests. The generated number always falls within the provided range of values.

Dart Random Number Generator Example

Dart’s dart:math library includes a Random class for random number generation. It offers the nextInt method, which accepts a maximum value and returns a random number.

int nextInt(int max)

The minimum number is implicitly taken as zero, while the maximum number is the given max value.

Here’s a simple example of generating random numbers:

import 'dart: math';

main() {
  var random = Random();
  print(random.nextInt(10)); //Random number between 0 to 10
  print(random.nextInt(100)); //Random number between 0 to 100
  print(random.nextInt(200)); //Random number between 0 to 100
  print(random.nextInt(1000)); //Random number between 0 to 1000
}
  • Import the dart:math package using the import keyword.
  • Create a Random variable using the var keyword.
  • Call nextInt() with the maximum range.
  • Random numbers are always generated between 0 and the provided maximum value.

Output:

4
70
47
294

Dart Random Number Generator within a Range Example

This example generates random numbers within a specified range between the minimum and maximum values.

import 'dart:math';

main() {
  var random = Random();
  int min = 10;
  int max = 20;
  var randomNumber = min + random.nextInt(max - min);
  print("$randomNumber is random number between $min and $max");
  print(randomNumber);
}

Output:

19 is a random number between 10 and 20
19

How to Generate a Random Number in Dart Excluding a Particular Number?

For instance, if you wish to generate a random number between 0 and 10, excluding the number 5, you can follow this example.

import 'dart:math';

main() {
  var random = Random();
  var excludeNumber = 5;
  var randomNumber;
  do {
    randomNumber = random.nextInt(10);
  } while (randomNumber == excludeNumber);
  print(randomNumber);
}