.indexWhere()

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Published Mar 5, 2024
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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.');
}
}

The above example returns the following output:

Index of the first negative integer: 3

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