Python Basics
Python Type Casting
Type casting means converting a value from one data type to another, and Python gives you simple built-in functions to do it on purpose.
What is Type Casting?
Sometimes the data type you have isn't the one you need — for example, input() always returns a string, even if the user typed a number. Type casting lets you convert that value into the correct type before using it.
Explicit Type Casting
Explicit casting means you deliberately convert a value using a built-in function like int(), float(), str() or list().
age_text = "25"
age_number = int(age_text)
print(age_number + 5) # 30
price = 99
price_text = str(price)
print("Price: " + price_text)
num = "3.14"
num_float = float(num)
print(num_float * 2)Converting to a List
The list() function converts other iterable data types, such as a string or tuple, into a list.
word = "abc"
letters = list(word)
print(letters) # ['a', 'b', 'c']Implicit Type Casting
Implicit casting happens automatically, without you writing any conversion code — Python does it behind the scenes when it is safe to do so, such as combining an int and a float in one expression.
whole = 5
decimal = 2.5
result = whole + decimal
print(result) # 7.5
print(type(result)) # <class 'float'>Python will NOT automatically convert a string number for math. "5" + 2 raises a TypeError — you must cast it explicitly with int("5") + 2.
Knowing when Python converts automatically versus when you must convert manually will save you from many common beginner errors.