Variables and Data Types

A variable is a name that refers to a value. You create one with the = sign. There is no need to say what type of value it holds; Python works that out for you.

city = "Pune"
population = 7_400_000
area_km2 = 331.3
is_capital = False

print(city, population, area_km2, is_capital)

Pune 7400000 331.3 False

The basic types

Every value has a type. You can ask for it with the type() function.

print(type("hello"))
print(type(42))
print(type(3.14))
print(type(True))

<class 'str'>
<class 'int'>
<class 'float'>
<class 'bool'>

• str holds text.
• int holds whole numbers of any size.
• float holds numbers with a decimal point.
• bool is either True or False.

Changing and converting values

A variable can be given a new value at any time. You can also turn one type into another with functions such as int(), float() and str().

score = 10
score = score + 5
print("Score:", score)

age_text = "21"
age = int(age_text)
print(age + 1)

price = 49.99
print("Price is " + str(price) + " rupees")

Score: 15
22
Price is 49.99 rupees

f-strings

Putting an f before a string lets you place variables straight inside it using curly braces. This is usually the neatest way to build a message.

name = "Meera"
marks = 87.456
print(f"{name} scored {marks:.1f} marks")

Meera scored 87.5 marks

The :.1f part means "show one digit after the decimal point".