What is an Array?

Arrays are one of the most commonly used data structures in computer programming. An array is a collection of variables permanently of the same type and stored in sequential memory locations. Arrays allow for efficient retrieval and manipulation of data as well as for storage optimization.

To create an array, you will typically declare a variable with the keyword “array” and specify the type of elements the array will store. You can also specify the size of the array. For example:

int[] nums = new int[5];

This declares an array of integers named “nums” that can store up to 5 elements. An array can grow or shrink as needed, so the size of the array doesn’t need to be set when it is declared.

Once an array is created, you can access individual elements using its index. The index of the first element in an array is 0 (zero). For example, to access the second element of the above array, you would use the statement:

int num2 = nums[1];

In addition to accessing individual elements, you can also loop through every element of an array using a for loop. This is useful when you want to apply some kind of operation to all elements of an array, such as a calculation.

Here is an example of a for loop iterating over the above array to calculate the sum:

int sum = 0;
for (int i = 0; i < nums.length; i++) {
sum += nums[i];
}

Another common use of arrays is multidimensional arrays. These are just like regular arrays but they can contain multiple dimensions. A two-dimensional array consists of rows and columns, like a spreadsheet.

For example, a two-dimensional array might hold information about cities and their populations:

string[,] cities = new string[3,3] { {“New York, NY”, “8,622,698”},
{“Los Angeles, CA”, “4,094,764”},
{“Chicago, IL”, “2,716,450”} };

You can access and manipulate elements of a multidimensional array using multiple indexes. For example, to access the population of Los Angeles, you would use the statement:

string popString = cities[1,1];

Arrays are a powerful and flexible data structure that allows you to store and retrieve data quickly and efficiently. From a simple one-dimensional array to a complex multidimensional array, you can use them to store and manipulate all kinds of data.