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In Python, keywords are reserved words that have special meanings. These words are part of the language syntax and cannot be used as identifiers (variable names, function names, etc.). Keywords help define the structure and functionality of Python programs.

we’ll cover:

  • What keywords are.
  • A list of Python keywords.
  • Examples of how to use them effectively.

What are Python Keywords?

Keywords in Python:

  • Are predefined and reserved by the language.
  • Cannot be used for anything other than their intended purpose.
  • Are case-sensitive (e.g., if is a keyword, but If is not).

List of Python Keywords

As of Python 3.10, here is the complete list of keywords:

Keywords Description
False, True Boolean values, representing truth and falsehood.
None Represents the absence of a value.
and, or, not Logical operators for combining Boolean expressions.
if, elif, else Conditional statements.
for, while, break, continue Loop control keywords.
in, is Membership and identity operators.
def, return, yield Define functions and return values.
class, del, pass Define classes, delete objects, or skip code.
try, except, finally, raise Handle exceptions and errors.
import, from, as Import modules or rename them.
with, async, await Context managers and asynchronous programming.
global, nonlocal Modify the scope of variables.
lambda Create anonymous (inline) functions.
assert Debugging tool to test conditions.

To view keywords in your Python environment, use the keyword module:


import keyword
print(keyword.kwlist)  # Prints all Python keywords

Using Python Keywords: Examples

Let’s explore some of these keywords with examples.

1. Conditional Statements

Keywords: if, elif, else

Conditional statements are used to execute code based on conditions.


age = 18

if age < 18:
    print("You are a minor.")
elif age == 18:
    print("You just became an adult!")
else:
    print("You are an adult.")

2. Loops

Keywords: for, while, break, continue

Loops allow you to repeat actions. Use break to exit a loop early and continue to skip the rest of the current iteration.

Example:


# Using for loop
for i in range(5):
    if i == 3:
        break  # Exit the loop when i is 3
    print(i)

# Using while loop
x = 0
while x < 5:
    x += 1
    if x == 3:
        continue  # Skip the rest of the iteration when x is 3
    print(x)

3. Boolean Values and Logical Operators

Keywords: True, False, and, or, not

These keywords are used in logical expressions.

Example:


is_raining = False
is_weekend = True

if not is_raining and is_weekend:
    print("Perfect day for a picnic!")
else:
    print("Stay indoors.")

4. Defining Functions

Keywords: def, return

Functions are reusable blocks of code. Use return to send a result back to the caller.

Example:


def greet(name):
    return f"Hello, {name}!"

print(greet("Alice"))  # Output: Hello, Alice!

5. Exception Handling

Keywords: try, except, finally, raise

Handle runtime errors using exception handling keywords.

Example:


try:
    num = int(input("Enter a number: "))
    print(f"The number you entered is {num}")
except ValueError:
    print("That's not a valid number!")
finally:
    print("Program execution completed.")

6. Classes

Keywords: class, pass

Create custom objects with classes. Use pass as a placeholder when no code is needed.

Example:


class Person:
    pass  # Placeholder for future code

person = Person()
print(type(person))  # Output: <class '__main__.Person'>

7. Global and Local Scopes

Keywords: global, nonlocal

Control variable scope with global and nonlocal.

Example:


# Using global
x = 10

def update_global():
    global x
    x = 20

update_global()
print(x)  # Output: 20

# Using nonlocal
def outer():
    y = 5
    def inner():
        nonlocal y
        y = 10
    inner()
    print(y)

outer()  # Output: 10

8. Lambda Functions

Keyword: lambda

Create small, anonymous functions using lambda.

Example:


square = lambda x: x ** 2
print(square(4))  # Output: 16

9. Context Management

Keyword: with

Use with for handling resources like file operations.

Example:


with open("example.txt", "w") as file:
    file.write("Hello, World!")  # Automatically closes the file

10. Importing Modules

Keywords: import, from, as

Import modules and rename them if needed.

Example:


import math as m

print(m.sqrt(16))  # Output: 4.0

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