GetUpperBound

GetUpperBound is a method of the System.Array class in the .NET framework and .NET Core. It returns the upper bound, i.e., the largest valid index, for a specified dimension of a multidimensional array.

Signature and usage: int GetUpperBound(int dimension). The dimension parameter is zero-based and must be in the range from 0 to Rank - 1, where Rank is the number of dimensions in the array. The method is an instance method; it is called on an array reference, for example: myArray.GetUpperBound(0).

Return value and behavior: GetUpperBound returns the upper bound for the given dimension. If the length of the specified dimension is zero, the method returns -1. For a typical non-empty array, this value equals the length of the dimension minus one. In a two-dimensional array declared as int[,] a = new int[4, 9], a.GetUpperBound(0) returns 3 and a.GetUpperBound(1) returns 8.

Exceptions and constraints: If dimension is less than 0 or greater than or equal to Rank, GetUpperBound throws ArgumentOutOfRangeException. The method applies to multidimensional arrays; jagged arrays (arrays of arrays) are not directly addressed by GetUpperBound for inner dimensions.

Related concepts: GetLowerBound(int dimension) returns the corresponding lower bound for a dimension (often 0 in .NET), and the Rank property indicates the number of dimensions. Length gives the total number of elements across all dimensions.

Overview: GetUpperBound is commonly used in loops and array-processing code to determine the last valid index for iteration, complementing GetLowerBound and Rank to navigate arrays reliably.