Skip to content
Interview Prep Buddy LogoInterview Prep Buddy

Python REPL

Python REPL

Section titled “Python REPL”

Introduction

Section titled “Introduction”

REPL = Read → Evaluate → Print → Loop

It’s an interactive shell where you type Python code and see results immediately.

Starting the REPL

Section titled “Starting the REPL”
Terminal window
python3          # Linux/macOS
python           # Windows

You’ll see:

Python 3.12.0 (main, ...)
Type "help", "copyright", "credits" or "license" for more information.
>>>

REPL Examples

Section titled “REPL Examples”
>>> 2 + 3
5
>>> name = "Alice"
>>> f"Hello, {name}!"
'Hello, Alice!'
>>> [x**2 for x in range(5)]
[0, 1, 4, 9, 16]
>>> import math
>>> math.pi
3.141592653589793

Special Commands

Section titled “Special Commands”
>>> help(str)           # Get help for str class
>>> dir(str)            # List all methods of str
>>> type(42)            # Check type
<class 'int'>
>>> _                   # Last result
>>> quit() or exit()    # Exit REPL

IPython: Enhanced REPL

Section titled “IPython: Enhanced REPL”
Terminal window
pip install ipython
ipython

Features: tab completion, syntax highlighting, magic commands, better errors.

In [1]: %timeit [x**2 for x in range(1000)]
# 78.8 µs ± 1.42 µs per loop

Why It Matters

Section titled “Why It Matters”

The REPL is perfect for experimenting, testing snippets, learning, and debugging.

Practice Exercises

Section titled “Practice Exercises”
  1. Use the REPL to calculate compound interest for a $10,000 investment at 7% for 10 years.
  2. Explore the math module using dir(math) and help(math.sqrt).
  3. Install IPython and use %timeit to compare two different approaches to a problem.