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In Chapter 3, “Components of C#,” you learned about some of the components of C#, such as classes, namespaces, and interfaces. In Chapter 4, you will learn about other components provided by C#. These components include arrays, collections, and indexers. This chapter will also cover data conversion by using box-
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We introduced the concept of arrays in Chapter 2, “C# Basics,” in the section |
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“Arrays.”This section will look at arrays in detail. An array is a data structure used |
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Single-Dimensional Arrays
A single-dimensional ar ray has an index attached to its elements. You can initialize a single-dimensional array as follows:
<data type> [] <array1> = new <data type> [size];
Here, data type is the type of data stored in the array, and size defines the number of elements in the array.
Multidimensional Arrays
A multidimensional ar ray has more than one index associated with its elements. C# supports two types of multidimensional arrays:
Rectangular array
Orthogonal or jagged array
A rectangular array has an equal number of columns in each row. An array of rank two is called a two-dimensional array. Therefore, a two-dimensional rectangular
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array will have two columns in each row. Look at the following statement that declares a two-dimensional rectangular array of three rows.
int [,] Integer = { {2,3}, {3,4}, {4,5} };
The dimension of an array is not specified while declaring an array. However, the dimension of an array is defined by the number of commas (,) in an array declaration statement. Look at the following example to declare a three-dimensional array with three rows.
int [, ,] Integer = { {1,2,3}, {2,3,4}, {3,4,5} };
In C#, you can initialize an array by using a for loop.
int [,] Integer = new int [5,10]; for (int x = 0; x < 5; x++)
{
for (int y = 0; y < 10; y++) Integer [x,y] = x*y;
}
The previous code creates a two-dimensional array with five rows and 10 columns. The variables x and y denote the number of rows and columns, respectively, in the array Integer. The values of x and y change in a for loop. The elements of the array are initialized by the product of the values of the variables x and y.
As discussed earlier, C# also supports orthogonal or jagged arrays. An orthogonal array can have a different number of columns in each row. Therefore, while declaring a jagged array, you specify only the number of rows in the array. Just as in a rectangular array, you do not use commas to declare an orthogonal array. Instead, the dimension of a jagged array is specified by the number of square brackets ([]).
int [] [] Integer = new int [2] []; Integer [0] = new int [2];
Integer [1] = new int [5];
This code declares a two-dimensional array with two rows.The first row contains two columns and the second row contains five columns.
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After declaring an array, you need to perform operations on the array. To do this, C# provides you with several methods. Some of the commonly used methods in arrays are discussed in the next section.
Methods in Arrays
An array in C# is an object and, therefore, has its own methods. Now look at some of the common methods used with arrays.
The Length property is used to determine the size or number of elements in an array. To find out the number of elements in the one-dimensional array Integer, you use the following statement:
int I = Integer.Length;
In this code, the Length property derives the size of the array Integer, which is then stored in the integer variable I.
Similarly, to determine the size of a multidimensional array, you use the GetLength() method.The GetLength() method returns the number of elements in a specified dimension of a multidimensional array. The dimension of the array is specified as a parameter to the GetLength() method.
int I = Integer.GetLength (1);
Here, the GetLength() method is used to find out the size of the second dimension of the multidimensional array Integer. The number of elements in the second dimension of the array are then stored in the integer variable I.
You can use the Reverse() method to reverse the order of the elements of an array. The Reverse() method is a static method, so the elements of an array that need to be reversed are sent as a parameter to the Reverse() method.
Array.Reverse (Integer);
This code reverses the order of the elements of the array. The name of the array is passed as a parameter to the method.
The elements of an array can be sorted using the Sort() method. Similar to the Reverse() method, the name of the array to be sorted is sent as a parameter to the method Sort(). The Sort() method arranges the elements of an array in ascending order. The elements of the array Integer can be sorted as: