{"id":68,"date":"2025-10-21T04:29:19","date_gmt":"2025-10-21T04:29:19","guid":{"rendered":"https:\/\/codetypingpro.com\/?p=68"},"modified":"2025-12-17T07:47:27","modified_gmt":"2025-12-17T07:47:27","slug":"lesson-12-exception-handling-in-python","status":"publish","type":"post","link":"https:\/\/codetypingpro.com\/?p=68","title":{"rendered":"Lesson 12: Exception Handling in Python"},"content":{"rendered":"\n

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

To understand how to handle errors<\/strong> in Python gracefully using exceptions<\/strong>, preventing program crashes and improving reliability.<\/p>\n\n\n\n

\n\n\n\n

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

An exception<\/strong> is an error that occurs during program execution<\/strong>.
Examples: dividing by zero, file not found, invalid input, etc.<\/p>\n\n\n\n

\u2705 Example:<\/strong><\/p>\n\n\n\n

num = 10\nprint(num \/ 0)  # This will raise ZeroDivisionError\n<\/code><\/pre>\n\n\n\n
Output:<\/strong><\/p>\n\n\n\n
ZeroDivisionError: division by zero\n<\/code><\/pre>\n\n\n\n
\n\n\n\n
\u2699\ufe0f 2. Try and Except Block<\/strong><\/h2>\n\n\n\n
Use try<\/code> to test code and except<\/code> to handle exceptions.<\/p>\n\n\n\n
try:\n    num = int(input(\"Enter a number: \"))\n    print(10 \/ num)\nexcept ZeroDivisionError:\n    print(\"Cannot divide by zero!\")\nexcept ValueError:\n    print(\"Invalid input! Enter an integer.\")\n<\/code><\/pre>\n\n\n\n
Behavior:<\/strong><\/p>\n\n\n\n
    \n
  • If input is 0 \u2192 prints “Cannot divide by zero!”<\/li>\n\n\n\n
  • If input is not a number \u2192 prints “Invalid input! Enter an integer.”<\/li>\n<\/ul>\n\n\n\n
    \n\n\n\n
    \ud83d\udd04 3. Handling Multiple Exceptions<\/strong><\/h2>\n\n\n\n
    You can handle multiple exceptions in one block.<\/p>\n\n\n\n
    try:\n    x = int(input(\"Enter a number: \"))\n    y = int(input(\"Enter another number: \"))\n    result = x \/ y\nexcept (ZeroDivisionError, ValueError) as e:\n    print(\"Error occurred:\", e)\nelse:\n    print(\"Result is:\", result)\nfinally:\n    print(\"Execution finished.\")\n<\/code><\/pre>\n\n\n\n
    \n\n\n\n
    \ud83e\uddf0 4. Common Built-in Exceptions<\/strong><\/h2>\n\n\n\n
    Exception<\/th>Cause<\/th>Example<\/th><\/tr><\/thead>
    ZeroDivisionError<\/code><\/td>Division by zero<\/td>10\/0<\/code><\/td><\/tr>
    ValueError<\/code><\/td>Invalid value<\/td>int(\"abc\")<\/code><\/td><\/tr>
    FileNotFoundError<\/code><\/td>File doesn\u2019t exist<\/td>open(\"nofile.txt\")<\/code><\/td><\/tr>
    TypeError<\/code><\/td>Wrong data type<\/td>\"5\" + 5<\/code><\/td><\/tr>
    IndexError<\/code><\/td>Invalid index<\/td>arr[10]<\/code><\/td><\/tr>
    KeyError<\/code><\/td>Key not found in dict<\/td>dict[\"x\"]<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
    \n\n\n\n
    \ud83d\udd01 5. Try, Except, Else, Finally<\/strong><\/h2>\n\n\n\n
    try:\n    num = int(input(\"Enter a number: \"))\n    result = 10 \/ num\nexcept ZeroDivisionError:\n    print(\"Cannot divide by zero!\")\nelse:\n    print(\"Division successful, result:\", result)\nfinally:\n    print(\"End of program\")\n<\/code><\/pre>\n\n\n\n
      \n
    • try<\/code>: code that may raise an exception<\/li>\n\n\n\n
    • except<\/code>: code to handle exception<\/li>\n\n\n\n
    • else<\/code>: runs if no exception occurs<\/li>\n\n\n\n
    • finally<\/code>: always runs<\/li>\n<\/ul>\n\n\n\n
      \n\n\n\n
      \ud83e\udde9 6. Raising Exceptions<\/strong><\/h2>\n\n\n\n
      You can raise exceptions intentionally using raise<\/code>.<\/p>\n\n\n\n
      age = int(input(\"Enter your age: \"))\nif age < 18:\n    raise ValueError(\"Age must be 18 or above.\")\n<\/code><\/pre>\n\n\n\n
      \n\n\n\n
      \ud83c\udf0d 7. Real-Life Example \u2013 Safe Input<\/strong><\/h2>\n\n\n\n

      <\/p>\n\n\n\n
      while True:\n    try:\n        num = int(input(\"Enter a positive number: \"))\n        if num < 0:\n            raise ValueError(\"Number cannot be negative\")\n        break\n    except ValueError as e:\n        print(\"Error:\", e)\n\nprint(\"You entered:\", num)<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
      \ud83c\udfaf Lesson Objective To understand how to handle errors in Python gracefully using exceptions, preventing program crashes and improving reliability. \ud83e\udde9 1. What Is an Exception? An exception is an error that occurs during program execution.Examples: dividing by zero, file not found, invalid input, etc. \u2705 Example: Output: \u2699\ufe0f 2. Try and Except Block Use […]<\/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-68","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\/68","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=68"}],"version-history":[{"count":1,"href":"https:\/\/codetypingpro.com\/index.php?rest_route=\/wp\/v2\/posts\/68\/revisions"}],"predecessor-version":[{"id":69,"href":"https:\/\/codetypingpro.com\/index.php?rest_route=\/wp\/v2\/posts\/68\/revisions\/69"}],"wp:attachment":[{"href":"https:\/\/codetypingpro.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=68"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/codetypingpro.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=68"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/codetypingpro.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=68"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}