getLength

GetLength is a method of the System.Array class in the .NET framework and .NET Core/.NET 5+ that returns the number of elements in a specified dimension of an array. It has the signature int GetLength(int dimension) and is invoked on an array instance.

Usage and behavior: For a multi-dimensional array, GetLength(dimension) returns the size of the given dimension. For example, in a two-dimensional array int[,] matrix = new int[3, 4], matrix.GetLength(0) returns 3 (the number of rows) and matrix.GetLength(1) returns 4 (the number of columns). The valid dimension values range from 0 to Rank − 1; passing a value outside this range throws ArgumentOutOfRangeException.

Relation to other array properties: GetLength is distinct from the Length property of Array. Length returns the total number of elements in the entire array (the product of all dimensions). For jagged arrays (arrays of arrays), Length refers to the length of the outer array, not the total count of inner elements. There is also GetLongLength(int dimension), which returns a long to support very large arrays.

Related concepts: GetUpperBound(int dimension) provides the upper bound index for a given dimension, which is typically GetLength(dimension) − 1. GetLength is not related to strings, which use the Length property to report character count.

See also: Length, GetLongLength, GetUpperBound, Rank.