Dart Runes takeWhile()
Syntax & Examples

Runes.takeWhile() method

The `takeWhile` method in Dart returns a lazy iterable of the leading elements of the original iterable that satisfy a specified test function.

Syntax of Runes.takeWhile()

The syntax of Runes.takeWhile() method is:

 Iterable<int> takeWhile(bool test(int value))

This takeWhile() method of Runes returns a lazy iterable of the leading elements satisfying test.

Parameters

ParameterOptional/RequiredDescription
testrequiredA function that takes an integer element as input and returns a boolean value indicating whether the element satisfies the test.

Return Type

Runes.takeWhile() returns value of type Iterable<int>.


✐ Examples

1 Take digits

In this example,

  1. We create a sequence of Unicode code points runes from the string '123Hello'.
  2. We use the takeWhile method with a test function to take all digits (ASCII values less than 58).
  3. We then print the taken digits to standard output.

Dart Program

void main() {
  Runes runes = Runes('123Hello');
  Iterable<int> taken = runes.takeWhile((element) => element < 58);
  print('Taken digits: $taken');
}

Output

Taken digits: (49, 50, 51)

2 Take characters less than 'a'

In this example,

  1. We create a sequence of Unicode code points characters from the string 'abc123'.
  2. We use the takeWhile method with a test function to take all characters with ASCII values less than 97 (lowercase letters).
  3. We then print the taken characters to standard output.

Dart Program

void main() {
  Runes characters = Runes('abc123');
  Iterable<int> takenChars = characters.takeWhile((element) => element < 97);
  print('Taken characters: $takenChars');
}

Output

Taken characters: (97, 98, 99)

Summary

In this Dart tutorial, we learned about takeWhile() method of Runes: the syntax and few working examples with output and detailed explanation for each example.