arraylength

Arraylength is a term used to describe the number of elements contained in an array or array-like structure. It is usually represented as a property or function in various programming languages, with naming conventions such as length, size, or GetLength. In practice, arraylength indicates how many items the container currently holds, which may differ from its capacity in dynamic structures.

Access to arraylength is typically constant time. In many languages the value is read-only and reflects the current state of the array. However, some languages treat length as adjustable: for example, JavaScript exposes an array.length property that can be read and assigned to, where reducing length truncates the array and increasing length creates new, empty slots. In other languages, such as Java or C#, the length of a fixed-size array is a constant field (array.length or Array.length), while dynamic collections expose a separate count property or method (for example, List or similar structures).

Dimensional arrays add nuance to arraylength. For single-dimensional arrays, length is a single number. In multi-dimensional or jagged arrays, length may refer to the size of a particular dimension, or to the count of top-level elements. Some languages provide specialized methods to query lengths along a given dimension (for instance, GetLength in certain .NET languages).

Common pitfalls include off-by-one errors, especially in languages where indexing starts at zero, and misconceptions about whether length equals capacity. Also, in languages with mutable length, extending or truncating arrays can leave gaps or require initialization of new elements.

See also: dynamic arrays, fixed-size arrays, array bounds, and language-specific array APIs.