{"id":94,"date":"2025-10-25T06:53:29","date_gmt":"2025-10-25T06:53:29","guid":{"rendered":"https:\/\/codetypingpro.com\/?p=94"},"modified":"2025-12-17T07:49:19","modified_gmt":"2025-12-17T07:49:19","slug":"lesson-24-logging-and-debugging-in-python","status":"publish","type":"post","link":"https:\/\/codetypingpro.com\/?p=94","title":{"rendered":"Lesson 24: Logging and Debugging in Python"},"content":{"rendered":"\n

<\/h3>\n\n\n\n

\ud83c\udfaf Lesson Objective<\/strong><\/h3>\n\n\n\n

To understand how to find and fix errors efficiently<\/strong> using debugging tools and how to track program execution<\/strong> using Python\u2019s logging<\/code> module.<\/p>\n\n\n\n

\n\n\n\n

\ud83e\udde9 1. What Is Debugging?<\/strong><\/h2>\n\n\n\n

Debugging<\/strong> is the process of identifying and fixing bugs (errors) in your code.<\/p>\n\n\n\n

Common debugging techniques:<\/p>\n\n\n\n

    \n
  • Using print()<\/code> statements<\/li>\n\n\n\n
  • Using Python\u2019s built-in pdb<\/code><\/strong> (Python Debugger)<\/li>\n\n\n\n
  • Using IDEs like VS Code or PyCharm with breakpoints<\/strong><\/li>\n\n\n\n
  • Using the logging<\/code><\/strong> module for professional tracking<\/li>\n<\/ul>\n\n\n\n
    \n\n\n\n

    \u2699\ufe0f 2. Common Types of Errors<\/strong><\/h2>\n\n\n\n
    Error Type<\/th>Description<\/th>Example<\/th><\/tr><\/thead>
    SyntaxError<\/strong><\/td>Invalid Python syntax<\/td>print(\"Hello\"<\/code><\/td><\/tr>
    NameError<\/strong><\/td>Variable not defined<\/td>print(x)<\/code><\/td><\/tr>
    TypeError<\/strong><\/td>Invalid type operation<\/td>\"5\" + 2<\/code><\/td><\/tr>
    ValueError<\/strong><\/td>Wrong type of value<\/td>int(\"abc\")<\/code><\/td><\/tr>
    ZeroDivisionError<\/strong><\/td>Division by zero<\/td>10 \/ 0<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
    \n\n\n\n

    \ud83e\udde0 3. Simple Debugging Using print()<\/code><\/strong><\/h2>\n\n\n\n
    def divide(a, b):\n    print(f\"Dividing {a} by {b}\")\n    return a \/ b\n\nprint(divide(10, 2))\nprint(divide(10, 0))  # Error: division by zero\n<\/code><\/pre>\n\n\n\n
    Problem:<\/strong> Works for quick checks but not for large or production programs.
    \u2705 Solution:<\/strong> Use the logging<\/code><\/strong> module.<\/p>\n\n\n\n
    \n\n\n\n
    \ud83e\uddfe 4. Introduction to Logging<\/strong><\/h2>\n\n\n\n
    Logging records events that happen during program execution<\/strong>, making it easier to:<\/p>\n\n\n\n
      \n
    • Diagnose issues<\/li>\n\n\n\n
    • Record user activity<\/li>\n\n\n\n
    • Track performance and errors<\/li>\n<\/ul>\n\n\n\n
      import logging\n<\/code><\/pre>\n\n\n\n
      \n\n\n\n
      \ud83e\uddf1 5. Basic Logging Example<\/strong><\/h2>\n\n\n\n
      import logging\n\nlogging.basicConfig(level=logging.INFO)\nlogging.info(\"Program started successfully\")\nlogging.warning(\"Low disk space\")\nlogging.error(\"File not found!\")\n<\/code><\/pre>\n\n\n\n
      Output:<\/strong><\/p>\n\n\n\n
      INFO:root:Program started successfully\nWARNING:root:Low disk space\nERROR:root:File not found!\n<\/code><\/pre>\n\n\n\n
      \n\n\n\n
      \ud83e\uddf0 6. Logging Levels<\/strong><\/h2>\n\n\n\n
      Level<\/th>Description<\/th>Usage<\/th><\/tr><\/thead>
      DEBUG<\/code><\/td>Detailed information (for developers)<\/td>Code tracing<\/td><\/tr>
      INFO<\/code><\/td>Confirmation that things are working<\/td>Status updates<\/td><\/tr>
      WARNING<\/code><\/td>Something unexpected happened<\/td>Potential problems<\/td><\/tr>
      ERROR<\/code><\/td>Serious issue, program may continue<\/td>Error handling<\/td><\/tr>
      CRITICAL<\/code><\/td>Very serious error<\/td>Program crash alerts<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
      Example:<\/p>\n\n\n\n
      logging.debug(\"This is a debug message\")\nlogging.info(\"Program is running fine\")\nlogging.warning(\"Low memory\")\nlogging.error(\"An error occurred\")\nlogging.critical(\"System failure!\")\n<\/code><\/pre>\n\n\n\n
      \n\n\n\n
      \ud83e\udeb6 7. Writing Logs to a File<\/strong><\/h2>\n\n\n\n
      import logging\n\nlogging.basicConfig(filename=\"app.log\",\n                    level=logging.DEBUG,\n                    format=\"%(asctime)s - %(levelname)s - %(message)s\")\n\nlogging.info(\"Application started\")\nlogging.warning(\"Disk usage high\")\nlogging.error(\"Error while processing data\")\n<\/code><\/pre>\n\n\n\n
      Creates a file:<\/strong> app.log<\/code>
      Example log:<\/strong><\/p>\n\n\n\n
      2025-10-25 10:15:23,123 - INFO - Application started\n2025-10-25 10:15:23,456 - WARNING - Disk usage high\n2025-10-25 10:15:23,789 - ERROR - Error while processing data\n<\/code><\/pre>\n\n\n\n
      \n\n\n\n
      \ud83e\uddee 8. Logging in Try\u2013Except Blocks<\/strong><\/h2>\n\n\n\n
      import logging\n\nlogging.basicConfig(level=logging.ERROR,\n                    format=\"%(asctime)s - %(levelname)s - %(message)s\")\n\ntry:\n    result = 10 \/ 0\nexcept ZeroDivisionError as e:\n    logging.error(\"Division by zero error: %s\", e)\n<\/code><\/pre>\n\n\n\n
      Output:<\/strong><\/p>\n\n\n\n
      2025-10-25 12:34:56,789 - ERROR - Division by zero error: division by zero\n<\/code><\/pre>\n\n\n\n
      \n\n\n\n
      \ud83d\udc1e 9. Debugging with pdb<\/code> (Python Debugger)<\/strong><\/h2>\n\n\n\n
      You can use the Python debugger<\/strong> to pause execution and inspect variables step-by-step.<\/p>\n\n\n\n
      import pdb\n\ndef add_numbers(a, b):\n    pdb.set_trace()  # Debug breakpoint\n    return a + b\n\nprint(add_numbers(5, 10))\n<\/code><\/pre>\n\n\n\n
      \ud83d\udd39 Commands inside pdb<\/code>:<\/p>\n\n\n\n
      Command<\/th>Meaning<\/th><\/tr><\/thead>
      n<\/code><\/td>Next line<\/td><\/tr>
      c<\/code><\/td>Continue execution<\/td><\/tr>
      p variable<\/code><\/td>Print variable value<\/td><\/tr>
      q<\/code><\/td>Quit debugging<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
      \n\n\n\n
      \ud83d\udca1 10. Example \u2013 Logging in a Real Program<\/strong><\/h2>\n\n\n\n
      import logging\n\nlogging.basicConfig(filename=\"bank.log\", level=logging.INFO,\n                    format=\"%(asctime)s - %(levelname)s - %(message)s\")\n\nclass BankAccount:\n    def __init__(self, name, balance):\n        self.name = name\n        self.balance = balance\n        logging.info(f\"Account created for {self.name} with balance {self.balance}\")\n\n    def deposit(self, amount):\n        self.balance += amount\n        logging.info(f\"{self.name} deposited {amount}. New balance: {self.balance}\")\n\n    def withdraw(self, amount):\n        if amount > self.balance:\n            logging.warning(f\"{self.name} tried to withdraw {amount} but insufficient funds.\")\n        else:\n            self.balance -= amount\n            logging.info(f\"{self.name} withdrew {amount}. Remaining: {self.balance}\")\n\nacc = BankAccount(\"Sameer\", 1000)\nacc.deposit(500)\nacc.withdraw(2000)\n<\/code><\/pre>\n\n\n\n
      Log File (bank.log<\/code>):<\/strong><\/p>\n\n\n\n
      2025-10-25 12:40:05,123 - INFO - Account created for Sameer with balance 1000\n2025-10-25 12:40:05,456 - INFO - Sameer deposited 500. New balance: 1500\n2025-10-25 12:40:05,789 - WARNING - Sameer tried to withdraw 2000 but insufficient funds.\n<\/code><\/pre>\n\n\n\n
      \n\n\n\n
      <\/h2>\n","protected":false},"excerpt":{"rendered":"
      \ud83c\udfaf Lesson Objective To understand how to find and fix errors efficiently using debugging tools and how to track program execution using Python\u2019s logging module. \ud83e\udde9 1. What Is Debugging? Debugging is the process of identifying and fixing bugs (errors) in your code. Common debugging techniques: \u2699\ufe0f 2. Common Types of Errors Error Type Description […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6,1],"tags":[],"class_list":["post-94","post","type-post","status-publish","format-standard","hentry","category-python-easy-course-outline","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/codetypingpro.com\/index.php?rest_route=\/wp\/v2\/posts\/94","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/codetypingpro.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/codetypingpro.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/codetypingpro.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/codetypingpro.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=94"}],"version-history":[{"count":1,"href":"https:\/\/codetypingpro.com\/index.php?rest_route=\/wp\/v2\/posts\/94\/revisions"}],"predecessor-version":[{"id":95,"href":"https:\/\/codetypingpro.com\/index.php?rest_route=\/wp\/v2\/posts\/94\/revisions\/95"}],"wp:attachment":[{"href":"https:\/\/codetypingpro.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=94"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/codetypingpro.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=94"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/codetypingpro.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=94"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}