Variables in Python

Variables –

Variables in python provides a way to associate names with objects. In python, we do not need to declare a variable before using them or declare it’s type as compared to other programming languages.

To create a variable, you have to write

a = 10
b = 20
c = a + b

Here, a , b and c are three variables that we have created. And if you print their values you will get

print("a:", a)
print("b:", b)
print("c:", c)

output - 
a: 10
b: 20
c: 30

The assignment operator = assign name to the left of the = symbol with the object to the right of = symbol.

Now, if I change the value of the variable a to 20 and print the result. You will see that value of a is equal to 20 but the value of c is still 30.

a = 20
print("a:", a)
print("b:", b)
print("c:", c)

output - 
a: 20
b: 20
c: 30

To change the value of c after the new assignment of a, we need to call c again.

c = a + b
print("a:", a)
print("b:", b)
print("c:", c)

output - 
a: 20
b: 20
c: 40

You can also assign a single value to multiple variables at once like this

a = b = c = 50
print("a:", a)
print("b:", b)
print("c:", c)

output - 
a: 50
b: 50
c: 50

or assign different values to multiple variables at once like this

a , b, c = 100, 200, "python"
print("a:", a)
print("b:", b)
print("c:", c)

output - 
a: 100
b: 200
c: python

And you don’t have to always assign numbers to a variable, you can assign any other data types like strings, boolean values, lists , dictionary etc. Here we assigned a string to the c variable. In our upcoming posts we will look at various data types in python so make sure to checkout our blog later or subscribe below to get notified.

Rules for creating variables –

There are few rules that you have to follow when creating variables otherwise python will throw errors.

1 . Variable names can contain only letters, numbers, and underscores. They can start with a letter or an underscore, but not with a number. For example a1 is a valid variable name but 1a is not.

2 . Spaces are not allowed in variable names, but you can use underscores to separate words in variable names. For example add_two_numbers

3 . You can not use reserve words in python for variable names like def, assert, global etc.

4 . Variable names are case sensitive. a and A is two different variable, they are not same.