List<> Capacity returns more items than added

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北海茫月
北海茫月 2020-12-06 16:58

There are several properties on List that seem to be related to number of items in the list - Capacity, Count (which is prese

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  •  误落风尘
    2020-12-06 17:29

    Here's the full explanation for the Capacity property from MSDN:


    Capacity is the number of elements that the List can store before resizing is required, while Count is the number of elements that are actually in the List.

    Capacity is always greater than or equal to Count. If Count exceeds Capacity while adding elements, the capacity is increased by automatically reallocating the internal array before copying the old elements and adding the new elements.

    The capacity can be decreased by calling the TrimExcess() method or by setting the Capacity property explicitly. When the value of Capacity is set explicitly, the internal array is also reallocated to accommodate the specified capacity, and all the elements are copied.

    Retrieving the value of this property is an O(1) operation; setting the property is an O(n) operation, where n is the new capacity.

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