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Dart if & else statements

last modified December 27, 2020

Dart if & else statements tutorial shows how to create conditions and branches in Dart.

Dart if & else

The if statement specifies the conditional execution of a block. If the expression evaluates to true, the block is executed. If the else statement is present and the if statement evaluates to false, the block following else is executed.

There can be multiple if/else statements.

Dart if/else examples

The following examples demonstrate conditional execution of blocks with if/else.

if_stm.dart
void main() {
  var num = 4;

  if (num > 0) {
    print("The number is positive");
  }
}

In the example we have a simple condition; if the num variable is positive, the message "The number is positive" is printed to the console. Otherwise; nothing is printed.

$ dart if_stm.dart
The number is positive

The message is printed since value 4 is positive.

if_else.dart
void main() {
  var num = -4;

  if (num > 0) {
    print("The number is positive");
  } else {
    print("The number is negative");
  }
}

Now we have added the second branch. The else statement specifies the block that is executed if the if condition fails.

$ dart if_else.dart
The number is negative

For the -4 value, the "The number is negative" is printed.

if_else2.dart
import 'dart:math';

void main() {
  const int MAX = 10;
  var num = new Random().nextInt(MAX) - 5;

  if (num > 0) {
    print("The number is positive");
  } else if (num == 0) {
    print("The number is zero");
  } else {
    print("The number is negative");
  }
}

In this example, we add additional branch with if else. We generate random values between -5 and 4. With the help of the if & else statement we print a message for all three options.

In this tutorial, we have covered conditions in Dart.

List all Dart tutorials.