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Variables are values stored in computer memory. We need to use them
for almost every program to allow the Robocore to remember things.
There are various different types of values, for example strings,
which are text values, and integers, which are whole number values.
The
computer needs you to tell it what type of value you want to use,
otherwise it will get confused.
Each
type of variable has its uses and limitations, which is why there are
simple methods for switching between variable types. This was shown in
the last tutorial, lets look at that program again line by line.
The
Dim lines declare the variables, that means they set them up for use
in the program. The type of variable must be specified using the ' As
' keyword. Here we have an integer and a string.
Here
the integer variable is used, this is because mathematical functions
can be performed using it such as multiplication
Using
the CStr statement the integer value held in answerI is converted into
a string and held in answer, this is a text variable allowing the
answer to be printed to the screen using debug.print.
Variables can have nearly any name, but you cannot use words that are
otherwise used in the programming language, and it is best to keep
them simple, either a single letter, or a word describing what the
variable does.
Other
types of variables are available. One of the types used commonly in
robotics is the Boolean variable. This provides us with a true or
false value.
For
example a bump sensor will either be pressed or not pressed, so the
Boolean variable for it will either be true (pressed) or false.
We
set up Boolean variables using the following statement
Boolean logic is commonly used with conditional statements, these are
covered in the next section.
There
is also the Single variable type, which allows floating point numbers
e.g 2.43 or -0.66, this is occasionally useful in robotics when more
maths is necessary. |
