Defining and declaring variables:
Data type is an important component of every programming
language, which tells the compiler, the type of data that can be stored in the
variables. What is a variable then? It is a container that holds the particular
type of data.
Consider a container, that is made only to hold water with
maximum capacity of 10 liters. So, now we can pour water in to that container
till the maximum limit. Depends on the requirement, up to 10 liters of water can be
stored.
Similarly, datatype
is like a container that is made only to hold water i.e. only a specific type
of data can be stored. The popular data types, used by programming languages
are int, float, char, double etc.
Then what is a variable, it is name of the container that
holds the water, let’s name that as Water Container. In programming, it is
defined as below,
int water_container;
in the above expression int is a datatype and
water_container is a variable. Int can hold only integers.
Consider we are storing 2 liters of water in the container,
how can we do that,
int water_container = 2; int can store only some particular
bits of data which of integer type.
So, to store extra amount of amount, we need a larger
container, similar to that, to store high volumes of data, we need to use other
data types. This is the basic for all the programming languages.
In INFO-BASIC, the datatype need not to be explicitly
mentioned as like in other programming languages.
You can just say, water_container =2;
This means, BASIC is not a strongly typed language. So, you
need to care about the data type of a variable. What will you do if you want
store some characters in water_container variable.
water-container = “2 liters”
Even a string can be stored in the same variable as shown
above. That’s all about data type. Give a name to the variable and store some
value in it, no need to specific what type of data you are storing in BASIC.
What is a constant?
Let’s consider the value of Pi. Everyone knows it is 3.14.
So, these values are constants and never be changed. But a data stored in a
variable can be changed.
If you are doing some mathematical calculations, that has Pi
constant, how to ensure that the value of Pi remains unchanged till the end of
the program. To achieve this EQU should be used. What does this EQU mean, it is
nothing but EQUATE. We are equating a value to a variable to make it constant.
Below is code representation,
EQU pi TO 3.14
This statement stores 3.14 in a memory located named as pi.
Interesting! Have you noticed, EQU and TO in the above
statements are capitalized. Yes, because these are keywords.
What is a keyword? Does it is something special to do with my code.
Keywords are reserved words for special purposes. We used
EQU to equate the value 3.14 to pi. “TO” is also capitalized. Because it is
keyword too. There many keywords in BASIC and we will come across in the forth coming
chapters. Very important, these keywords should not be used as a variable.
Do you have questions, please comment below? We will respond
to you at the earliest.
Comments
Post a Comment