
Booleans are one of the most important building blocks in Python programming. They help make decisions, control program flow, and evaluate conditions.
In this article, you'll learn:
-
What Boolean values are
-
How to use them in conditions
-
Boolean operators
-
Truthy and falsy values
-
Tips and common mistakes
What Are Booleans?
A Boolean represents one of two values:
-
True
-
False
They are part of Python’s built-in data types.
is_sunny = True
is_raining = False
Note: Boolean values are capitalized (True
, not true
).
Type and Identity
x = True
print(type(x)) # <class 'bool'>
Behind the scenes:
True == 1 # True
False == 0 # True
So you can use them in mathematical operations:
print(True + True) # 2
print(False * 10) # 0
Booleans in Conditionals
Booleans are mostly used in if
statements and loops:
is_logged_in = True
if is_logged_in:
print("Welcome!")
else:
print("Please log in.")
Comparison Operators
These operators return a Boolean result:
Operator | Meaning | Example | Result |
---|---|---|---|
== |
Equal to | 5 == 5 |
True |
!= |
Not equal to | 5 != 3 |
True |
> |
Greater than | 5 > 3 |
True |
< |
Less than | 3 < 5 |
True |
>= |
Greater or equal | 5 >= 5 |
True |
<= |
Less or equal | 3 <= 4 |
True |
⚙️ Logical Operators
Used to combine multiple conditions:
Operator | Description | Example |
---|---|---|
and |
True if both are True | True and False → False |
or |
True if at least one is True | True or False → True |
not |
Inverts the result | not True → False |
age = 25
has_ticket = True
if age >= 18 and has_ticket:
print("You can enter.")
Truthy and Falsy Values
In conditions, not only True
and False
matter. Other values are treated as Boolean based on their truthiness.
✅ These are considered False
:
-
None
-
False
-
0
,0.0
-
""
(empty string) -
[]
,{}
,()
(empty containers)
Everything else is True
.
if []:
print("This won't run.")
else:
print("Empty list is falsy.") # This will print
Boolean in Loops
Booleans control loops like while
:
is_running = True
while is_running:
user_input = input("Type 'exit' to stop: ")
if user_input == "exit":
is_running = False
Boolean Conversion with bool()
Use bool()
to test any value’s truthiness:
print(bool(0)) # False
print(bool("Hello")) # True
print(bool([])) # False
Example: Login Validator
username = input("Enter username: ")
password = input("Enter password: ")
if username == "admin" and password == "123":
print("Login successful!")
else:
print("Access denied.")
Tips for Working with Booleans
-
Use
is
for comparing toTrue
/False
only if you're checking identity (rare). -
Avoid
== True
or== False
. Use the value directly:if is_ready: # ✔️ Better than if is_ready == True
-
Remember: short-circuiting applies with
and
andor
.
⚠️ Common Pitfalls
Mistake | Problem | Correct Way |
---|---|---|
if x == True: |
Redundant | if x: |
is True instead of == |
Identity check, not value | Use == or direct test |
Misunderstanding 0 , '' , [] |
They evaluate to False |
Use bool() to check |
Chaining logic incorrectly | if a and b or c may confuse |
Use parentheses: if a and (b or c) |
Summary
Concept | Example |
---|---|
Boolean values | True , False |
Logic operators | and , or , not |
Falsy values | 0 , None , "" , [] , {} |
Use in if |
if condition: |
bool() function |
bool("abc") → True |
What’s Next?
After mastering Booleans, you'll be ready to dive deeper into:
-
Control structures (
if
,elif
,else
) -
Loops (
while
,for
) -
Boolean expressions in functions and validations
Tips and Tricks
What is pass in Python?
Python | Pass Statement
The pass statement is used as a placeholder for future code. It represents a null operation in Python. It is generally used for the purpose of filling up empty blocks of code which may execute during runtime but has yet to be written.
def myfunction():
pass
How can you generate random numbers?
Python | Generate random numbers
Python provides a module called random using which we can generate random numbers. e.g: print(random.random())
We have to import a random module and call the random() method as shown below:
import random
print(random.random())
The random() method generates float values lying between 0 and 1 randomly.
To generate customized random numbers between specified ranges, we can use the randrange() method
Syntax: randrange(beginning, end, step)
import random
print(random.randrange(5,100,2))
What is lambda in Python?
Python | Lambda function
A lambda function is a small anonymous function. This function can have any number of parameters but, can have just one statement.
Syntex:
lambda arguments : expression
a = lambda x,y : x+y
print(a(5, 6))
It also provides a nice way to write closures. With that power, you can do things like this.
def adder(x):
return lambda y: x + y
add5 = adder(5)
add5(1) #6
As you can see from the snippet of Python, the function adder takes in an argument x and returns an anonymous function, or lambda, that takes another argument y. That anonymous function allows you to create functions from functions. This is a simple example, but it should convey the power lambdas and closures have.
What is swapcase() function in the Python?
Python | swapcase() Function
It is a string's function that converts all uppercase characters into lowercase and vice versa. It automatically ignores all the non-alphabetic characters.
string = "IT IS IN LOWERCASE."
print(string.swapcase())
How to remove whitespaces from a string in Python?
Python | strip() Function | Remove whitespaces from a string
To remove the whitespaces and trailing spaces from the string, Python provides a strip([str]) built-in function. This function returns a copy of the string after removing whitespaces if present. Otherwise returns the original string.
string = " Python "
print(string.strip())
What is the usage of enumerate() function in Python?
Python | enumerate() Function
The enumerate() function is used to iterate through the sequence and retrieve the index position and its corresponding value at the same time.
lst = ["A","B","C"]
print (list(enumerate(lst)))
#[(0, 'A'), (1, 'B'), (2, 'C')]
Can you explain the filter(), map(), and reduce() functions?
Python | filter(), map(), and reduce() Functions
- filter() function accepts two arguments, a function and an iterable, where each element of the iterable is filtered through the function to test if the item is accepted or not.
>>> set(filter(lambda x:x>4, range(7))) # {5, 6}
-
map() function calls the specified function for each item of an iterable and returns a list of result
>>> set(map(lambda x:x**3, range(7))) # {0, 1, 64, 8, 216, 27, 125}
-
reduce() function reduces a sequence pair-wise, repeatedly until we arrive at a single value..
>>> reduce(lambda x,y:y-x, [1,2,3,4,5]) # 3
Let’s understand this:
2-1=1
3-1=2
4-2=2
5-2=3Hence, 3.
What is a namedtuple?
Python | namedtuple
A namedtuple will let us access a tuple’s elements using a name/label. We use the function namedtuple() for this, and import it from collections.
>>> from collections import namedtuple
#format
>>> result=namedtuple('result','Physics Chemistry Maths')
#declaring the tuple
>>> Chris=result(Physics=86,Chemistry=92,Maths=80)
>>> Chris.Chemistry
# 92
Write a code to add the values of same keys in two different dictionaries and return a new dictionary.
We can use the Counter method from the collections module
from collections import Counter
dict1 = {'a': 5, 'b': 3, 'c': 2}
dict2 = {'a': 2, 'b': 4, 'c': 3}
new_dict = Counter(dict1) + Counter(dict2)
print(new_dict)
# Print: Counter({'a': 7, 'b': 7, 'c': 5})
Python In-place swapping of two numbers
Python | In-place swapping of two numbers
>>> a, b = 10, 20
>>> print(a, b)
10 20
>>> a, b = b, a
>>> print(a, b)
20 10
Reversing a String in Python
Python | Reversing a String
>>> x = 'PythonWorld'
>>> print(x[: : -1])
dlroWnohtyP
Python join all items of a list to convert into a single string
Python | Join all items of a list to convert into a single string
>>> x = ["Python", "Online", "Training"]
>>> print(" ".join(x))
Python Online Training
python return multiple values from functions
Python | Return multiple values from functions
>>> def A():
return 2, 3, 4
>>> a, b, c = A()
>>> print(a, b, c)
2 3 4
Python Print String N times
Python | Print String N times
>>> s = 'Python'
>>> n = 5
>>> print(s * n)
PythonPythonPythonPythonPython
Python check the memory usage of an object
Python | Check the memory usage of an object
>>> import sys
>>> x = 100
>>> print(sys.getsizeof(x))
28