Declaring a variable and its type

Every variable that we want to use in a script must be declared in a statement. What does that mean? Well, before Unity can use a variable, we have to tell Unity about it first. Okay then, what are we supposed to tell Unity about the variable?

There are only three absolute requirements to declare a variable and they are as follows:

• We have to specify the type of data that a variable can store
• We have to provide a name for the variable
• We have to end the declaration statement with a semicolon

The following is the syntax we use to declare a variable:

typeOfData nameOfTheVariable;

Let's use one of the LearningScript variables as an example; the following is how we declare a variable with the bare minimum requirements:

int number1;

This is what we have:

• Requirement #1 is the type of data that number1 can store, which in this case is an int, meaning an integer
• Requirement #2 is a name, which is number1
• Requirement #3 is the semicolon at the end

The second requirement of naming a variable has already been discussed. The third requirement of ending a statement with a semicolon has also been discussed. The first requirement of specifying the type of data will be covered next.

The following is what we know about this bare minimum declaration as far as Unity is concerned:

• There's no public modifier, which means it's private by default
• It won't appear in the Inspector panel or be accessible from other scripts
• The value stored in number1 defaults to zero

The most common built-in variable types

This section shows only the most common built-in types of data that C# provides for us and variables can store.

Only these basic types are presented here so that you understand the concept of a variable being able to store only the type of the data that you specify. Custom types of data, which you will create later, will be discussed in Chapter 7, Creating the Gameplay is Just a Part of the Game in the Discussion on Dot Syntax.

The following chart shows the most common built-in types of data you will use in Unity:

Note

There are a few more built-in types of data that aren't shown in the preceding chart. However, once you understand the most common types, you'll have no problem looking up the other built-in types if you ever need to use them. You can also create your own classes and store their instances in variables.

We know the minimum requirements to declare a variable. However, we can add more information to a declaration to save time and coding. In LearningScript, we've already seen some examples of assigning values when the variable is being declared, and now we'll see some more examples.