C# | Getting an enumerator for a range of elements in the ArrayList
ArrayList.GetEnumerator(Int32, Int32) method is used to get an enumerator for a range of elements in the ArrayList.
public virtual System.Collections.IEnumerator GetEnumerator (int index, int count);
index: It is the zero-based starting index of type Int32 of the ArrayList section that the enumerator should refer to.
count: It is the number of elements of the type Int32 in the ArrayList section that the enumerator should refer to.
Return Value: This method returns an IEnumerator for the specified range of elements in the ArrayList.
- ArgumentOutOfRangeException: If the index or count is less than zero.
- ArgumentException: If the index and count do not specify a valid range in the ArrayList.
Below programs illustrate the use of above-discussed method:
14 45 78 48 49 51 77 After GetEnumerator(Int32, Int32) Method: 48 49
System.ArgumentOutOfRangeException: Non-negative number required.
Parameter name: index
- The foreach statement of the C# language hides the complexity of the enumerators. Therefore, using foreach is recommended, instead of directly manipulating the enumerator.
- Enumerators can be used to read the data in the collection, but they cannot be used to modify the underlying collection.
- Current returns the same object until either MoveNext or Reset is called. MoveNext sets Current to the next element.
- An enumerator remains valid as long as the collection remains unchanged. If changes are made to the collection, such as adding, modifying, or deleting elements, the enumerator is irrecoverably invalidated and its behavior is undefined.
- This method is an O(1) operation.