currentSize

CurrentSize is a variable or property used in programming to represent the number of elements currently stored in a collection, buffer, or container. It is typically distinct from the structure's total capacity or maximum allowed size. The concept appears in both low-level data structures and higher-level libraries that support dynamic growth. Maintaining a separate currentSize allows algorithms to distinguish between how much space is allocated and how much data is actually in use.

In many implementations, currentSize is updated on every insertion or deletion. When adding an element, the code checks whether currentSize < capacity; if so, the element is placed at the index currentSize and currentSize is incremented. If there is no room, the storage may be expanded before insertion. On removal, currentSize is decremented and the vacated slot can be reused or overwritten. A separate capacity value governs when reallocation occurs.

In languages with built-in dynamic collections, a method or property such as size(), length, or count returns the current number of elements; however, some custom containers still expose currentSize as a separate field for performance or clarity, and to keep a clear invariant between logical size and physical storage.

Examples of usage vary: in low-level C structures a dynamic array might store fields data, capacity, and currentSize; in Java, ArrayList backs storage with an internal array and a size field representing the number of elements; in C++, a vector maintains size and capacity and may be accessed via size() rather than a raw currentSize field.

Considerations include thread safety, invariants, and the potential for off-by-one errors. Reading currentSize should be synchronized with modifications to the underlying storage in concurrent contexts.