Types

So, what are types?

Types are these indicators of, well, type. A real world example could be the type Car. You probably know what a car is, but there are many different cars out there. In programming, they might all have the type of Car. You would need to specify this at the start of the line. Then, you would name your variable, maybe something like toyota or ford. At this point the compiler knows that your variable (let’s say, ford) will have the type Car. Next we can put the assignment operator, =. The compiler knows that stuff after the = will be ‘assigned’ to ford, and it should have the type Car. Let’s go over an example with a simple type that we use quite a bit.

boolean correct = true;

This example’s type is boolean. Boolean (also known as bool) values can hold either true, or false. This is seen with = true. Anything other than valid values on the right side of that = will probably cause an error. Let’s go over some more simple types.

int number = 3;
double decimal = 5.34;
String text = "Hello!";

These variables have names that explain what they hold, which is generally good practice. number, of type int, holds integer values, hence the type int. decimal of type double holds decimal values such as 3.14159 or 2.71828182. Finally, text of type String holds text values, which need to be surrounded by quotation marks, preferable ".

You can set these variables to values of the same type after you have declared them like above.

correct = false;
number = 8;
decimal = 4.999;
text = "Robots are cool";

Notice the absence of types at the start of the lines. This is because once you declare variables with a type, you don’t need to tell the computer that it’s that type anymore, it’ll keep track of it on its own.