# Python This guide quickly references essential Python syntax, functions, and concepts. Whether you are a beginner or an experienced developer, this cheat sheet will help you improve your Python skills. You'll find examples of basic syntax, data structures, control flow, functions, classes, and more. ### Basic Syntax #### Variables ```python x = 10 y = "Hello, World!" z = 3.14 ``` #### Data Types ```python integer = 10 floating_point = 3.14 string = "Hello" boolean = True list = [1, 2, 3] dictionary = {"key": "value"} tuple = (1, 2, 3) set = {1, 2, 3} ``` #### Control Structures **Conditional Statements** ```python if x > 5: print("x is greater than 5") elif x == 5: print("x is 5") else: print("x is less than 5") ``` **Loops** ```python for i in range(5): print(i) while x > 0: print(x) x -= 1 ``` #### Functions ```python def greet(name): return f"Hello, {name}!" print(greet("Alice")) ``` #### Classes ```python class Dog: def __init__(self, name, age): self.name = name self.age = age def bark(self): return f"{self.name} says woof!" dog = Dog("Buddy", 3) print(dog.bark()) ``` #### Sorting ```python sorted_list = sorted(my_list) sorted_dict = sorted(my_dict.items(), key=lambda item: item[1]) ``` #### Basic Input/Output ```python user_input = input("Enter your name: ") print("Hello,", user_input) ``` ### Working with Files #### Reading Files ```python with open("file.txt", "r") as file: content = file.read() print(content) ``` #### Writing Files ```python with open("file.txt", "w") as file: file.write("Hello, World!") ``` ### Networking #### HTTP Requests ```python import requests response = requests.get("http://example.com") print(response.status_code) print(response.text) ``` #### Socket Programming ```python import socket s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect(("example.com", 80)) s.sendall(b"GET / HTTP/1.1\r\nHost: example.com\r\n\r\n") response = s.recv(4096) print(response) s.close() ``` ### Security-Related Modules #### Hashing ```python import hashlib # MD5 hash_md5 = hashlib.md5(b"password").hexdigest() print(f"MD5: {hash_md5}") # SHA-256 hash_sha256 = hashlib.sha256(b"password").hexdigest() print(f"SHA-256: {hash_sha256}") ``` #### Encryption and Decryption **Using `cryptography` Library** ```python from cryptography.fernet import Fernet # Generate a key key = Fernet.generate_key() cipher_suite = Fernet(key) # Encrypt a message cipher_text = cipher_suite.encrypt(b"Secret message") print(f"Encrypted: {cipher_text}") # Decrypt the message plain_text = cipher_suite.decrypt(cipher_text) print(f"Decrypted: {plain_text}") ``` #### Password Hashing ```python from passlib.hash import pbkdf2_sha256 # Hash a password hashed = pbkdf2_sha256.hash("password") print(f"Hashed: {hashed}") # Verify a password is_correct = pbkdf2_sha256.verify("password", hashed) print(f"Password correct: {is_correct}") ``` ### Web Scraping #### Using `BeautifulSoup` ```python from bs4 import BeautifulSoup import requests response = requests.get("http://example.com") soup = BeautifulSoup(response.text, 'html.parser') for link in soup.find_all('a'): print(link.get('href')) ``` ### Working with JSON ```python import json # Parse JSON data = '{"name": "Alice", "age": 25}' parsed_data = json.loads(data) print(parsed_data) # Convert to JSON dict_data = {"name": "Bob", "age": 30} json_data = json.dumps(dict_data) print(json_data) ``` ### Command Execution #### Using `subprocess` Module ```python import subprocess # Run a command and get the output result = subprocess.run(["ls", "-la"], capture_output=True, text=True) print(result.stdout) ``` ### Regular Expressions ```python import re pattern = r"\b[A-Za-z]+\b" text = "The quick brown fox jumps over the lazy dog" matches = re.findall(pattern, text) print(matches) ``` ### Logging ```python import logging logging.basicConfig(level=logging.INFO) logging.info("This is an info message") logging.warning("This is a warning message") logging.error("This is an error message") ``` ### Useful Tips #### Virtual Environments ```sh # Create a virtual environment python -m venv venv # Activate the virtual environment # On Windows venv\Scripts\activate # On Unix or MacOS source venv/bin/activate # Install dependencies pip install -r requirements.txt # Deactivate the virtual environment deactivate ``` #### Exception Handling ```python try: result = 10 / 0 except ZeroDivisionError as e: print(f"Error: {e}") finally: print("This block is always executed") ``` #### List Comprehensions ```python squares = [x ** 2 for x in range(10)] print(squares) ``` #### Dictionary Comprehensions ```python squares_dict = {x: x ** 2 for x in range(10)} print(squares_dict) ``` #### Using `itertools` for Efficient Iteration ```python import itertools permutations = list(itertools.permutations([1, 2, 3])) print(permutations) combinations = list(itertools.combinations([1, 2, 3], 2)) print(combinations) ``` #### Using `collections` for Advanced Data Structures ```python from collections import Counter, defaultdict, deque # Counter counter = Counter("hello world") print(counter) # Defaultdict default_dict = defaultdict(int) default_dict["key"] += 1 print(default_dict) # Deque deque_list = deque([1, 2, 3]) deque_list.appendleft(0) print(deque_list) ``` #### Using `os` for System Operations ```python import os # Get current working directory cwd = os.getcwd() print(cwd) # List files in directory files = os.listdir(".") print(files) # Execute a system command os.system("echo Hello, World!") ``` ### Penetration Testing Tools #### `scapy` for Network Packet Manipulation ```python from scapy.all import * # Create a packet packet = IP(dst="192.168.1.1")/ICMP() # Send the packet send(packet) ``` #### `nmap` for Network Scanning ```python import nmap nm = nmap.PortScanner() nm.scan('127.0.0.1', '22-443') print(nm.csv()) ``` #### `socket` for Simple Network Connections ```python pythonCopy codeimport socket # Create a socket object s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) # Connect to a server s.connect(('localhost', 8080)) # Send data s.sendall(b'Hello, World!') # Receive data data = s.recv(1024) print('Received', repr(data)) # Close the connection s.close() ``` --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. 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