Dart Runes singleWhere()
Syntax & Examples

Runes.singleWhere() method

The `singleWhere` method in Dart returns the single element that satisfies the given predicate, or throws an error if none or more than one element matches the predicate.

Syntax of Runes.singleWhere()

The syntax of Runes.singleWhere() method is:

 int singleWhere(bool test(int element), { int orElse() })

This singleWhere() method of Runes returns the single element that satisfies 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.
orElseoptionalA function that returns an integer value to be used if no or more than one element satisfies the test.

Return Type

Runes.singleWhere() returns value of type int.


✐ Examples

1 Find character code

In this example,

  1. We create a sequence of Unicode code points runes from the string 'Hello'.
  2. We use the singleWhere method with a test function to find the single character code for 'H' (Unicode code point 72).
  3. We then print the character code to standard output.

Dart Program

void main() {
  Runes runes = Runes('Hello');
  int characterCode = runes.singleWhere((element) => element == 72);
  print('Character code: $characterCode');
}

Output

Character code: 72

2 Find digit

In this example,

  1. We create a sequence of Unicode code points numbers from the string '12345'.
  2. We use the singleWhere method with a test function to find the single digit '2' (Unicode code point 50).
  3. We then print the digit to standard output.

Dart Program

void main() {
  Runes numbers = Runes('12345');
  int digit = numbers.singleWhere((element) => element == 50);
  print('Digit: $digit');
}

Output

Digit: 50

Summary

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