The last topic I want to look at in this course is arrays. An array is a collection or group of variables all of the same type. Let's create another project called arrays. Again, I'll create that in Ubuntu using the .netnew command. Once .NET has created the project, I'll CD into the arrays directory and open Visual Studio Code, setting the working directory to the current one with the "." argument. I'll click Yes to add the assets necessary to build the Arrays application.

Remember, from the first course, I talked about args, an array of strings that are passed into the main procedure of a C# program. An array is declared by appending the data type with square brackets. Like args, I'm declaring an array of string called arrayOfStrings and initializing it with four elements, "how", "now", "brown", and "cow". An array must be initialized when declared, even if it is with no elements using empty curly braces.

Next, I'll declare an array of ints with 5 items and finally an empty array of chars. An array is not just a data storage structure but has properties that return information about the array as opposed to the data it contains. One of those properties is length. Using the length property, let's print out the size of each array with string interpolation. I've changed the color theme of VSCode from the previous demo, so the variables within the string are in a different color. This makes reading the code in quickly seeing what is a literal string and what is a variable much easier.

Now, let's print out all the elements of arrayOfStrings. The first array element is always accessed with the index zero, so the last element will be array length minus one; in this case, length 4 - 1 is 3. Next, I'll print the arrayOfInts elements starting with element one. The index for accessing an array element doesn't have to be a literal number. You can use a variable, even in the form of another array element. Here, I'm using arrayOfInts item 3, which contains the value 2, to access the third arrayOfStrings item. Yes, a little bit meta, but it illustrates the use of dynamic indexes and the zero index first element. Here we go, "how", "now", "brown", "cow".

Let's assign that third string element to a string variable called cowColor. ArrayOfLetters has been declared as empty, so it doesn't actually exist in memory yet. I'll create a new array of char with the same length as the cowColor variable by specifying the array size within square brackets after the data type.

Once the array exists, we can assign values to the elements, so the letter "c" to the first element. We can assign values to arrayOfLetters by accessing the cowColor string variable in the same way we access an array. Fundamentally a string is a special array of char. When I write out all arrayOfLetters elements, we essentially output a string. Arrays can be multi-dimensional, so two or more dimensions.

A two-dimensional array is analogous to a checker or chessboard, so you specify an element with two indexes, like coordinates. Declare a two-dimensional array using square brackets called checkers, but this time with a comma to separate the dimensions and assign a new int array specifying each dimension's length to be 4. I'll assign a value to each array element specifying the first dimension index and then the second separated by a comma.

Once all elements have a value, I'll print them all out, one dimension per line, and print a separating line before the checkerboard. Let's run that to see the checkerboard pattern printed to the console.