Python True: The True Keyword in Python
In Python, True is a built-in constant that represents the boolean value of true. Alongside False, True enables logical and conditional operations.
How to Use True in Python
You can assign True directly to a variable or get True as a result of comparisons or logical operations.
python
is_authenticated = True
is_positive = 100 > 0
When to Use True in Python
The True keyword is fundamental when you need to make decisions based on truth conditions. Here are some common applications:
Conditional Statements
True is essential for if statements and other conditional statements in Python. If the condition of an if statement evaluates to True, the block of code below the if statement executes. Otherwise the lines of code below the else statement execute.
python
feature_enabled = True
if feature_enabled:
print("Feature is on.") # This line executes
else:
print("Feature is off.")
Comparisons
Comparisons return True if the evaluated condition meets the criteria set by the comparison operator.
For example, in a benefit-check scenario, you might compare the age of a user with a certain threshold age.
python
age = 70
if age >= 65:
print("Qualifies for senior benefits.") # This line will execute because the comparison evaluates to True
While Loops
In a Python while loop, a condition needs to be True for the loop to continue or execute in the first place.
At some point, however, the condition needs to become False, or the loop needs to trigger a break statement. If the condition always evaluates to True, the loop becomes infinite (“infinite loop”).
python
while True:
response = input("Enter 'quit' to exit: ")
if response == 'quit':
break
Logical Operations
Logical operations with boolean operators allow you to combine, invert, or compare boolean expressions. The three boolean operators in Python are and, or, and not.
True plays a key role in logical operations, helping to evaluate the truth of expressions.
python
a = True
b = False
result1 = a and b # Result is False because both operands are not True
result2 = a or b # Result is True because one operand is True
result3 = a and not b # Result is True because a is True and b is not True
Examples of True in Python
You’ll find the True keyword in virtually every Python application. Here are some popular examples:
Input Validation
True often signifies a valid condition in input validation scenarios.
python
user_input = "valid"
while True:
if user_input:
break # Exit if input is non-empty
user_input = input("Please enter a valid input: ")
User Authentication
True can control the flow of execution within a program, for example based on a user’s authentication status.
python
logged_in = True
if logged_in:
print("You're logged in.")
else:
print("You need to log in.")
Function Return Values
Functions might return True to indicate success or validity.
python
def check_prime(number):
if number > 1:
for i in range(2, number):
if (number % i) == 0:
return False
return True
else:
return False
print(check_prime(11)) # Output: True
Learn More About True in Python
Python False to True Conversion
You can convert False to True using the not operator. Inverting is useful when you need the opposite of a boolean expression or value.
python
is_active = True
is_inactive = not is_active # Converts True to False
True in Data Structures
Within data structures, True often represents the presence or truth of an element.
python
user_permissions = {"read": True, "write": False} # 'read' permission is True
Truthy Values in Python
Besides the explicit True keyword, the Python programming language evaluates several other values as True in logical operations. These “truthy” values include non-zero numbers, non-empty strings, lists, tuples, dictionaries, and sets.
Using truthy values makes Python code concise and expressive, enabling easier and more readable condition checks.
python
my_list = [1, 2, 3]
if my_list: # Evaluates to True because the list is not empty
print("The list is not empty.")