We are again implementing an even number functionality. We simply use the yield keyword to return each item that we want to be included in the final result set.
NET for most scenarios. We can find this interface in the System. Notice we are filtering the numbers with a Where clause, and then performing a ToList operation, before printing out the numbers. This interface resides in the System. In this example, we are adding the number to our collection, and removing the number 1. As expected, the output is 2, 3, 5, Often when we have items from multiple sources, we need to add items to existing sequences, so having this functionality is a very useful feature.
Returns a new enumerable collection that contains the elements from source with the last count elements of the source collection omitted. Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements. The element's index is used in the logic of the predicate function. Computes the sum of the sequence of Decimal values that are obtained by invoking a transform function on each element of the input sequence. Computes the sum of the sequence of Double values that are obtained by invoking a transform function on each element of the input sequence.
Computes the sum of the sequence of Int32 values that are obtained by invoking a transform function on each element of the input sequence. Computes the sum of the sequence of Int64 values that are obtained by invoking a transform function on each element of the input sequence.
Computes the sum of the sequence of nullable Decimal values that are obtained by invoking a transform function on each element of the input sequence. Computes the sum of the sequence of nullable Double values that are obtained by invoking a transform function on each element of the input sequence. Computes the sum of the sequence of nullable Int32 values that are obtained by invoking a transform function on each element of the input sequence.
Computes the sum of the sequence of nullable Int64 values that are obtained by invoking a transform function on each element of the input sequence. Computes the sum of the sequence of nullable Single values that are obtained by invoking a transform function on each element of the input sequence. Computes the sum of the sequence of Single values that are obtained by invoking a transform function on each element of the input sequence.
Returns a new enumerable collection that contains the last count elements from source. Returns elements from a sequence as long as a specified condition is true. Filters a sequence of values based on a predicate.
Each element's index is used in the logic of the predicate function. Applies a specified function to the corresponding elements of two sequences, producing a sequence of the results. Returns a new queryable sequence that contains the elements from source plus the specified element appended at the end. Converts an IEnumerable to an IQueryable. Computes the average of a sequence of Decimal values that is obtained by invoking a projection function on each element of the input sequence.
Computes the average of a sequence of Double values that is obtained by invoking a projection function on each element of the input sequence.
Computes the average of a sequence of Int32 values that is obtained by invoking a projection function on each element of the input sequence. Computes the average of a sequence of Int64 values that is obtained by invoking a projection function on each element of the input sequence. Computes the average of a sequence of nullable Decimal values that is obtained by invoking a projection function on each element of the input sequence.
Computes the average of a sequence of nullable Double values that is obtained by invoking a projection function on each element of the input sequence. Computes the average of a sequence of nullable Int32 values that is obtained by invoking a projection function on each element of the input sequence.
Computes the average of a sequence of nullable Int64 values that is obtained by invoking a projection function on each element of the input sequence. Computes the average of a sequence of nullable Single values that is obtained by invoking a projection function on each element of the input sequence. Computes the average of a sequence of Single values that is obtained by invoking a projection function on each element of the input sequence.
Converts the elements of an IQueryable to the specified type. Split the elements of a sequence into chunks of size at most size. Returns the first element of a sequence that satisfies a specified condition or a default value if no such element is found. Groups the elements of a sequence and projects the elements for each group by using a specified function.
Key values are compared by using a specified comparer. Keys are compared by using a specified comparer. Keys are compared by using a specified comparer and the elements of each group are projected by using a specified function. Returns an Int64 that represents the number of elements in a sequence that satisfy a condition. Filters the elements of an IQueryable based on a specified type.
Returns a new queryable sequence that contains the elements from source plus the specified element prepended at the beginning. The resulting values from each intermediate sequence are combined into a single, one-dimensional sequence and returned.
A result selector function is invoked on each element of each intermediate sequence, and the resulting values are combined into a single, one-dimensional sequence and returned. Determines whether two sequences are equal by using the default equality comparer to compare elements. Returns a new queryable sequence that contains the elements from source with the last count elements of the source queryable sequence omitted. Computes the sum of the sequence of Decimal values that is obtained by invoking a projection function on each element of the input sequence.
Computes the sum of the sequence of Double values that is obtained by invoking a projection function on each element of the input sequence. Computes the sum of the sequence of Int32 values that is obtained by invoking a projection function on each element of the input sequence. Computes the sum of the sequence of Int64 values that is obtained by invoking a projection function on each element of the input sequence.
Computes the sum of the sequence of nullable Decimal values that is obtained by invoking a projection function on each element of the input sequence. Computes the sum of the sequence of nullable Double values that is obtained by invoking a projection function on each element of the input sequence. Computes the sum of the sequence of nullable Int32 values that is obtained by invoking a projection function on each element of the input sequence.
Computes the sum of the sequence of nullable Int64 values that is obtained by invoking a projection function on each element of the input sequence. Hence, to achieve this, first I will create a new class Employee , with a few attributes. Once this class is ready, it is time to create an IEnumerable implementation for Employee. Hence, I will create a new class named EmployeeEnumerable.
This class will implement IEnumerable and provide an implementation of the GetEnumerator method of the IEnumerable interface. Apart from the methods needed for IEnumerable , I created an indexer method this[] for this class. I also created a property Count , returning the count of the Employee List.
We will need both of these properties when we will define the IEnumerator implementation. Now that the basic implementation for the EmployeeEnumerable class is ready. It is time to create a class to return the enumerator.
And for that I will create a new class EmployeeEnumerator. The class EmployeeEnumerator will implement the interface IEnumerator.
And I will give implementation for all the required methods for the IEnumerator interface. Note: I have also done the proper IDisposable pattern implementation in the above code. You can see the details of this pattern in my YouTube video here. Firstly, I declared two variables, currentIndex , which will keep the index of the item in the collection. And employees , which is an instance of EmployeeEnumerable.
Secondly, in the constructor, I am setting employees to the incoming EmployeeEnumerable parameter. And then, I am setting the currentIndex to And finally, setting the Current property, which returns an instance of Employee to default which will be null in this case.
Thirdly, in the MoveNext method, I am setting the current employee based on the currentIndex. And returning false if the current index is greater than the total employees.
Finally, in the Reset method, I am just setting the value of currentIndex back to Collections , IQueryable is located inside System. Linq namespace. I will explain later why! So as defined above, IEnumerable is a base class which represents a container.
Collections namespace. Using this type of a collection you can not add, edit, delete or count items after initial load of items. This way we prevent any modification to our items. We use this container just to contain a list of items and nothing more. In order to count our elements inside this type of a collection, we need to implement IEnumerator.
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