Types and Conversions¶

Every value in Python has a type. The type determines what you can do with it.

Learn Your Way¶

Read	Build	Watch	Test	Review	Visualize
You are here	Projects	Videos	Quiz	Flashcards	Diagrams

Visualize It¶

See how type conversions change values and what happens when they fail: Open in Python Tutor

Basic types¶

Type	What it holds	Examples
`str`	Text (string)	`"hello"`, `'world'`, `"123"`
`int`	Whole number	`42`, `-3`, `0`
`float`	Decimal number	`3.14`, `-0.5`, `2.0`
`bool`	True or False	`True`, `False`
`None`	Nothing / empty	`None`

Checking a type¶

print(type("hello"))   # <class 'str'>
print(type(42))        # <class 'int'>
print(type(3.14))      # <class 'float'>
print(type(True))      # <class 'bool'>

Converting between types¶

Function	Converts to	Example
`str()`	String	`str(42)` → `"42"`
`int()`	Integer	`int("42")` → `42`
`float()`	Float	`float("3.14")` → `3.14`
`bool()`	Boolean	`bool(0)` → `False`

Why conversion matters¶

input() always returns a string. If you want to do math with it, you must convert:

age_text = input("Age? ")     # User types 30 → age_text is "30" (string)
age = int(age_text)            # Convert to integer
print(age + 1)                 # 31 (math works now)

Without conversion:

print("30" + 1)  # TypeError: can only concatenate str to str

Truthy and falsy values¶

Python treats some values as True and others as False in conditions:

Falsy (treated as False): - False, 0, 0.0, "" (empty string), [] (empty list), {} (empty dict), None

Truthy (treated as True): - Everything else: True, any non-zero number, any non-empty string/list/dict

name = ""
if name:
    print("Has a name")
else:
    print("No name")      # This runs because "" is falsy

Common mistakes¶

Comparing different types:

"5" == 5     # False! String "5" is not the same as integer 5
int("5") == 5  # True — convert first

Converting non-numeric strings:

int("hello")   # ValueError: invalid literal
int("3.14")    # ValueError: cannot convert float string to int directly
float("3.14")  # 3.14 — use float() for decimal strings

Practice¶

Quick check: Take the quiz

Review: Flashcard decks Practice reps: Coding challenges

← Prev	Home	Next →