Values, Types & Expressions

Work confidently with numbers, strings, booleans, `None` and explicit type conversion.

By the end of this lesson

You will be able to

Identify common built-in types.
Convert text and numbers deliberately.
Use comparisons and boolean expressions to produce decisions.

A variable is a name bound to a value

Python names can refer to integers, floating-point values, strings, booleans and the special value None. Use type(value) while exploring unfamiliar data, but do not confuse a printed representation with a data contract.

count = 12
price = 4.5
city = "Delhi"
is_open = True
result = None

print(type(count))  # <class 'int'>
print(type(price))  # <class 'float'>

Convert at the boundary

Input read from a text file or terminal may arrive as a string. Convert it when you know what the value should mean, and handle invalid input explicitly rather than assuming every string contains a valid number.

raw_hour = "08"
hour = int(raw_hour)

raw_temperature = "23.5"
temperature = float(raw_temperature)

label = str(hour)
is_morning = hour < 12

Apply what you learned

Exercise

Build a small value parser

Write a function that receives raw text values for an hour and a temperature and returns typed values.

Convert the hour to an integer.
Convert the temperature to a float.
Check that the hour is between 0 and 23.
Return a clear error for invalid input.
Print the parsed values and their types.

Done when

Valid input produces an int hour and float temperature; invalid input does not fail silently.

Free references

Study resources

1 links

01
Built-in types Article
Focus on numeric types, text sequences, booleans, None, and type conversion.

Done

Check your understanding

Self-test

2 questions

Question 1

What type does input() return?
Question 2

What is the difference between == and is?

Completion check

Move on when

You can inspect, convert and validate basic values without relying on implicit assumptions.

Mark passed and continue Back to module