Dart .indexWhere()

In Dart, the .indexWhere() method is used to find the index of the first element in a list that fulfills a given condition. If the operation is successful, it returns the index. Otherwise, it returns -1.

Syntax

int indexWhere(bool func(S demo))

• func: A function that provides a condition for the .indexWhere() method to check.
• S: The type of element that is passed to the function.
• demo: The element that is passed to the function.

Example

In this example, the .indexWhere() method is used to find the index of the first negative integer in a list:

void main() {
  List<int> numbers = [8, 5, 2, -3, 6];
  int index = numbers.indexWhere((number) => number < 0);
  if (index != -1) {
    print('Index of the first negative integer: $index');
  } else {
    print('No negative integers found.');
  }
}

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The above example returns the following output:

Index of the first negative integer: 3

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