Variable -:

• A variable is a name which is given to any storage area or memory location in a program.

Actually, Variable doesn’t hold a value but it’s the name given to any memory address in RAM. It means variable is the way to access that memory address of Ram so that we can store and manipulate data in that memory address or memory block.

• It’s a name of memory location.

In simple words we can say that variable is a container which contains some kind of information and whenever we need that information then we simply use that container or open it.

Rules for defining a variable in Python :

• Variable name can contain alphabets, digits, and underscore (_).

For E.g. : demo_xyz = ‘It’s a string variable’

• Variable name can start with an alphabet and underscore only.

For E.g. : _demo, de_mo, etc.

• It can’t start with a digit.
• No white-space and reserved keywords are allowed to use as a variable name.

Python is an intelligent language i.e. it automatically defines the type of data. It means we just need to put some data in a variable then Python automatically understands what kind of data variable is holding.

type() Function : type() function is a special type of function which allow user to find data type of any variable or of any kind of data. It returns the data type of any data.

Note – We can’t do arithmetic operations with strings i.e. we can’t add a string to any number.

Note – We can add (concatenate) two or more strings as string and string can be concatenated and replicated.

Typecasting :

It is the way to change the data type of one data to another i.e. it changes the data type of any variable or data to any other data type.

I know it’s bit confusing but let me tell you in a simply manner. Suppose there is a string “34” and as we know we can’t add this to any integer number let’s say 6. But to do so we can typecast string to int data type and then we can add 34+6 and we will get the output as 40.

There are many functions to convert one data type into another type :

str() – this function allows us to convert data type into string.

int() – this function allows us to convert data type into integer.

float() – this function allows us to convert data type into floating point number i.e. no. with decimals.

input() Function – This function allow user to input something in the program as a string.

input() function always takes input as a string i.e. if we ask user to input a number then also it will take it as a string and then we have to typecast it into either int or float data type. 

Quiz : Create a program which takes two number input from user and then give output as a sum of these numbers.

Solution :