Method FindIndex

FindIndex<TSource>(IAsyncEnumerable<TSource>, Func<TSource, bool>, CancellationToken)

Searches for an element that matches the conditions defined by the specified predicate and returns the zero-based index of the first occurrence within the entire IAsyncEnumerable<T>.

Declaration

public static ValueTask<int> FindIndex<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, bool> predicate, CancellationToken cancellationToken = default)

Parameters

Type	Name	Description
IAsyncEnumerable<TSource>	source	The source sequence.
Func<TSource, bool>	predicate	The predicate that defines the conditions of the element to search for.
CancellationToken	cancellationToken	The optional cancellation token to be used for cancelling the sequence at any time.

Returns

Type	Description
ValueTask<int>	The zero-based index of the first occurrence of an element that matches the conditions defined by predicate within the entire IAsyncEnumerable<T>, if found; otherwise, -1.

Type Parameters

Name	Description
TSource	The type of elements of source

Remarks

The IAsyncEnumerable<T> is searched forward starting at the first element and ending at the last element.

The predicate is a delegate to a method that returns true if the object passed to it matches the conditions defined in the delegate. The elements of the current IAsyncEnumerable<T> are individually passed to the predicate delegate.

This operator executes immediately.

Exceptions

Type	Condition
ArgumentNullException	source or predicate is null.

FindIndex<TSource>(IAsyncEnumerable<TSource>, Func<TSource, bool>, Index, CancellationToken)

Searches for an element that matches the conditions defined by the specified predicate and returns the zero-based index of the first occurrence within the range of elements in the IAsyncEnumerable<T> that extends from the specified index to the last element.

Declaration

public static ValueTask<int> FindIndex<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, bool> predicate, Index index, CancellationToken cancellationToken = default)

Parameters

Type	Name	Description
IAsyncEnumerable<TSource>	source	The source sequence.
Func<TSource, bool>	predicate	The predicate that defines the conditions of the element to search for.
Index	index	The Index of the starting element within the sequence.
CancellationToken	cancellationToken	The optional cancellation token to be used for cancelling the sequence at any time.

Returns

Type	Description
ValueTask<int>	The zero-based index of the first occurrence of an element that matches the conditions defined by predicate within the the range of elements in the IAsyncEnumerable<T> that extends from index to the last element, if found; otherwise, -1.

Type Parameters

Name	Description
TSource	The type of elements of source

Remarks

The IAsyncEnumerable<T> is searched forward starting at index and ending at the last element.

The predicate is a delegate to a method that returns true if the object passed to it matches the conditions defined in the delegate. The elements of the current IAsyncEnumerable<T> are individually passed to the predicate delegate.

This operator executes immediately.

Exceptions

Type	Condition
ArgumentNullException	source or predicate is null.

FindIndex<TSource>(IAsyncEnumerable<TSource>, Func<TSource, bool>, Index, int, CancellationToken)

Searches for an element that matches the conditions defined by the specified predicate and returns the zero-based index of the first occurrence within the range of elements in the IAsyncEnumerable<T> that starts at the specified index to the last element and contains the specified number of elements.

Declaration

public static ValueTask<int> FindIndex<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, bool> predicate, Index index, int count, CancellationToken cancellationToken = default)

Parameters

Type	Name	Description
IAsyncEnumerable<TSource>	source	The source sequence.
Func<TSource, bool>	predicate	The predicate that defines the conditions of the element to search for.
Index	index	The Index of the starting element within the sequence.
int	count	The number of elements in the section to search.
CancellationToken	cancellationToken	The optional cancellation token to be used for cancelling the sequence at any time.

Returns

Type	Description
ValueTask<int>	The zero-based index of the first occurrence of an element that matches the conditions defined by predicate within the the range of elements in the IAsyncEnumerable<T> that that starts at index and contains count number of elements, if found; otherwise, -1.

Type Parameters

Name	Description
TSource	The type of elements of source

Remarks

The IAsyncEnumerable<T> is searched forward starting at index and ending at index plus count minus 1, if count is greater than 0.

The predicate is a delegate to a method that returns true if the object passed to it matches the conditions defined in the delegate. The elements of the current IAsyncEnumerable<T> are individually passed to the predicate delegate.

This operator executes immediately.

Exceptions

Type	Condition
ArgumentNullException	source or predicate is null.
ArgumentOutOfRangeException	count is less than 0.