Dart program to check if an integer is odd or even

Introduction:

The int class in Dart contains two properties to check if a number is even or odd. We can use these properties to find out quickly if a number is odd or even. In this tutorial, I will show you how to do that with an example:

Method 1: By using the isEven and isOdd properties:

A number is called an even number if it is perfectly divisible by 2. Else, it is called an odd number. The isEven and isOdd are two boolean properties defined in the int class. These properties of an integer can be used to check if a number is even or odd. The value of isEven is true for an even number. Else, it will be false. Similarly, the value of isOdd is true if it is an odd number, and it will be false otherwise.

Example program:

In the below example, we are taking one number as input from the user and it prints if the number is odd or even. It uses the isEven and isOdd properties to check if the number is even or odd.

import 'dart:io';

void main() {
  int? number;

  print("Enter a number : ");
  var data = stdin.readLineSync();

  number = int.tryParse(data ?? '-1');

  if (number == null) {
    print("Invalid input.");
  } else if (number.isEven) {
    print("$number is an even number");
  } else if (number.isOdd) {
    print("$number is an odd number");
  }
}

Download it on GitHub

Sample Output:

If you run the above program, it will give outputs as below:

Enter a number :
12
12 is an even number

Enter a number :
13
13 is an odd number

Note that it will also work for negative numbers. For example, -12 will be considered an even number.

Method 2: By using the modulo operator:

Another traditional way is to use the modulo operator, % to check if a number is even or odd. The modulo operator returns the remainder of a division operation. For an even number n, the value n%2 is 0. Similarly, for an odd number n, the value of n%2 is 1.

The following program shows how to use the modulo operator to check if a number is even or odd:

import 'dart:io';

void main() {
  int? number;

  print("Enter a number : ");
  var data = stdin.readLineSync();

  number = int.tryParse(data ?? '-1');

  if (number == null) {
    print("Invalid input.");
  } else if (number % 2 == 0) {
    print("$number is an even number");
  } else if (number % 2 == 1) {
    print("$number is an odd number");
  }
}

Download it on GitHub

If you run the above program, it will print the same output.

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