Python 3 — Fundamentals

Function

A block of reusable code that performs a specific task, defined using `def` keyword.

What is a Python module?

A file containing Python definitions and statements, intended to be imported and used in other Python programs.

Import statement

Used to include the functionality of a module into a Python program, using the `import` keyword.

What does `len()` do in Python?

Returns the number of items in an object like a list, tuple, or string.

Slice

A way to retrieve a portion of a sequence by specifying a start and end index: `sequence[start:end]`.

How does `if __name__ == '__main__':` work?

Determines if the Python file is being run as the main program. If true, it runs the code block under it.

Lambda function

An anonymous, inline function defined with the `lambda` keyword, consisting of a single expression.

What is list comprehension?

A concise way to create lists using a single line of code with a `for` loop inside brackets: `[x for x in range(5)]`.

Exception

An error that occurs during the execution of a program, disrupting normal flow.

Try-Except block

Used to handle exceptions in Python, allowing the program to continue execution.

What is a class in Python?

A blueprint for creating objects, encapsulating data and behavior.

Instance

An individual object created from a class.

Inheritance

A mechanism to create a new class using the properties and methods of an existing class.

What is a Python decorator?

A function that modifies the behavior of another function or method, often denoted with `@decorator_name`.

Global variable

A variable defined outside of a function, accessible throughout the program.

Local variable

A variable defined within a function, accessible only within that function.

What does `return` do in a function?

Sends a function's result back to the caller and exits the function.

Docstring

A string literal used to document a specific segment of code, written as the first statement in a function, module, or class.

What is `self` in a class method?

A reference to the current instance of the class, used to access instance variables and methods.

How do you comment a line in Python?

By using the `#` symbol at the beginning of the line.

Boolean

A data type that can be either `True` or `False`.

What is the `__init__` method?

A special method in Python classes used to initialize new instances, akin to a constructor.

For loop

A control flow statement used to iterate over a sequence, like a list or string.

While loop

A control flow statement that repeats a block of code as long as a condition is true.

Break statement

Terminates the nearest enclosing loop, allowing the program to proceed with the next statement outside the loop.

Continue statement

Skips the remaining code inside a loop for the current iteration and moves to the next iteration.

What is a set in Python?

An unordered collection of unique items, defined using curly braces: `{1, 2, 3}`.

What is Python's `range()` function?

Generates a sequence of numbers, often used in `for` loops.

File I/O

The process of reading from and writing to files using functions like `open()`, `read()`, and `write()`.

How does string formatting work with `f-strings`?

A way to embed expressions inside string literals, using `{}` brackets and prefixing the string with `f`.

What is a generator?

A function that returns an iterator and is defined using `yield` instead of `return`.

Mutable vs Immutable

Mutable objects can be changed after creation (e.g., lists), while immutable objects cannot (e.g., tuples).

What is the GIL in Python?

Global Interpreter Lock, a mutex that protects access to Python objects, preventing multiple native threads from executing Python bytecodes at once.

What is `pip`?

A package manager for Python that allows you to install and manage additional libraries and dependencies.

What is the difference between `==` and `is`?

`==` checks for value equality, while `is` checks for reference (identity) equality.