{"id":2791,"date":"2020-09-02T18:43:30","date_gmt":"2020-09-02T13:13:30","guid":{"rendered":"https:\/\/copyassignment.com\/?page_id=2791"},"modified":"2023-04-24T07:44:04","modified_gmt":"2023-04-24T02:14:04","slug":"exception-handling-in-python","status":"publish","type":"page","link":"https:\/\/copyassignment.com\/python\/exception-handling-in-python\/","title":{"rendered":"Exception Handling In Python"},"content":{"rendered":"\n\n\n

Definition<\/h2>\n\n\n\n

Exception Handling In <\/span><\/strong>Python<\/a><\/strong> <\/span>is one of the features of OOPS. It is mainly designed to handle runtime errors<\/span><\/strong> and the exceptions <\/span><\/strong>that corrupt <\/span><\/strong>the flow of the program. The general format is the usage of “try<\/span><\/strong>” and “except<\/span><\/strong>” keywords. There may be some block of code<\/span><\/strong> that may get an error during the runtime <\/span><\/strong>so we run that code inside the try block and if the code gets interrupted <\/span><\/strong>by any errors, it leaves the block and goes to the except block<\/span><\/strong>.<\/p>\n\n\n\n

Syntax:<\/h2>
try:\n    statements\nexcept:\n    statements\n<\/pre><\/strong>\n<\/div><\/div>\n\n\n\n
Example<\/h3>
try:\n    a = 5\n    b = 0\n    print(a\/b)\nexcept:\n    print(\"ZeroDivision Error\")\n<\/pre><\/strong>\n<\/div>
Output<\/h3>
ZeroDivision Error<\/pre><\/strong><\/div><\/div>\n\n\n\n
Explanation:<\/strong><\/h3>\n\n\n\n
In the try block<\/mark><\/strong>, the number is divided by zero<\/mark><\/strong> which faces an exception and moves to the except. Here, no specific error type is found, and prints the message passed in the except block.<\/p>\n\n\n\n
Keywords used with Exception Handling<\/h2>\n\n\n\n
There are 5 keywords that are mainly used in exception handling–<\/strong><\/p>\n\n\n\n
    \n
  • Try<\/span><\/strong><\/li>\n\n\n\n
  • Except<\/span><\/strong><\/li>\n\n\n\n
  • Else<\/span><\/strong><\/li>\n\n\n\n
  • Finally<\/span><\/strong><\/li>\n\n\n\n
  • raise<\/span><\/strong><\/li>\n<\/ul>\n\n\n\n
    Handling Common Errors<\/strong><\/h2>\n\n\n\n
    Some of the common types of errors that can be easily handled in Python are–<\/strong><\/p>\n\n\n\n
      \n
    • Arithmetic error<\/span><\/strong> \u2013 occurs when the arithmetic calculations fail.<\/li>\n\n\n\n
    • Overflow error<\/span><\/strong> \u2013 occurs when the input size exceeds the initialized size of the variable.<\/li>\n\n\n\n
    • Floating-point error<\/span><\/strong> \u2013 occurs when the calculation of floating-point values fails.<\/li>\n\n\n\n
    • Zero division error<\/span><\/strong> \u2013 occurs when the number is divided by zero.<\/li>\n\n\n\n
    • Import error<\/span><\/strong> \u2013 occurs when the import file is wrong or mismatched.<\/li>\n\n\n\n
    • Key error<\/span><\/strong> \u2013 occurs when the key is not found or mismatched in the dictionary.<\/li>\n\n\n\n
    • Name error<\/span><\/strong> –  occurs when the variable name is not found or mismatched.<\/li>\n\n\n\n
    • Syntax error<\/span><\/strong> \u2013 occurs when the syntax for the logic used is wrong.<\/li>\n\n\n\n
    • Type Error<\/span><\/strong> \u2013 occurs when the data types of the variables do not match.<\/li>\n\n\n\n
    • IO error<\/span><\/strong> \u2013 occurs when the input or output acts as expected.<\/li>\n\n\n\n
    • Value error<\/span><\/strong> \u2013 occurs when the object created to store the value does not exist or fails to store the value.<\/li>\n<\/ul>\n\n\n\n
      Example1<\/h3>
      try:\n    a = 10\n    b = \"9\"\n    print(a + b)\nexcept TypeError:\n    print(\"Type error encountered\")\n<\/pre><\/strong>\n<\/div>
      Output<\/h3>
      Type error encountered<\/pre><\/strong><\/div><\/div>\n\n\n\n
      Explanation<\/strong><\/h3>\n\n\n\n
      \n\n\n\n
      The variables a and b <\/strong>are of not the same type i.e. a is numeric<\/mark><\/strong> and b is a string<\/mark><\/strong>. Thus, there is a difference in the data type<\/mark><\/strong> of the two variables that’s why the code execution moves <\/mark><\/strong>to the except block<\/mark><\/strong> where the error is identified and prints the TypeError<\/mark><\/strong> message.<\/p>\n\n\n\n
      Example2<\/h3>
      try:\n    a=10\n    b='9'\n    c=0\n    print(a\/c)\n    print(a+b)\nexcept TypeError:\n    print('Type error encountered')\nexcept ZeroDivisionError:\n    print('Tried to divide the number by zero')\n<\/pre><\/strong>\n<\/div>
      Output<\/h3>
      Tried to divide the number by zero<\/pre><\/strong><\/div><\/div>\n\n\n\n
      Explanation<\/strong><\/h3>\n\n\n\n
      Here, two statements are present, one is\u00a0“dividing by zero<\/mark><\/strong>” and “adding a number with a string<\/mark><\/strong>“. In this case, when the first exception(a\/c)<\/mark><\/strong> is found in line 5, the flow of the program is broken and moves to the appropriate except<\/mark><\/strong> section.<\/p>\n\n\n\n
      The else Keyword<\/h2>\n\n\n\n
      The else keyword<\/span><\/strong> is used after the except block. The code flow is designed in such a way that, if the code does not face any exceptions<\/span><\/strong>\/runtime errors<\/span><\/strong> then, it moves to the else block after executing the try block<\/span><\/strong>, otherwise it goes to the except block<\/span><\/strong> and halts <\/span><\/strong>the execution of the program.<\/p>\n\n\n\n
      Syntax:<\/h2>
      try :\n     statements\nexcept:\n     statements\nelse:\n     statements\n<\/pre><\/strong>\n<\/div><\/div>\n\n\n\n
      Now, let’s see examples–<\/strong><\/p>\n\n\n\n
      Example1<\/h3>
      try:\n    a=10\n    b=0\n    c=4\n    print(a\/c)\nexcept ZeroDivisionError:\n    print('Tried to divide the number by zero')\nelse:\n    print('No exception found.. Entered else part')\n<\/pre><\/strong>\n<\/div>
      Output<\/h3>
      2.5\nNo exception found.. Entered else part<\/pre><\/strong><\/div><\/div>\n\n\n\n
      Explanation<\/strong><\/h3>\n\n\n\n
      The variables a <\/span><\/strong>and c <\/span><\/strong>are divided <\/span><\/strong>since the value of both are not 0 <\/span><\/strong>so it does not face exception and enter the else part<\/span><\/strong>.<\/p>\n\n\n\n
      Example2<\/h3>
      try:\n    a=10\n    b=0\n    c=4\n    print(a\/b)\nexcept ZeroDivisionError:\n    print('Tried to divide the number by zero')\nelse:\n    print('No exception found.. Entered else part')\n<\/pre><\/strong>\n<\/div>
      Output<\/h3>
      Tried to divide the number by zero<\/pre><\/strong><\/div><\/div>\n\n\n\n
      Explanation<\/strong><\/h3>\n\n\n\n
      Since the value of b <\/span><\/strong>is 0<\/span><\/strong>, it faces the zero division error<\/span><\/strong> and does not enter the else <\/span><\/strong>section.<\/p>\n\n\n\n
      The Finally Keyword<\/strong><\/h2>\n\n\n\n
      The finally keyword<\/span><\/strong> is placed at the end of the program. It will be executed no matter exception occurs or not.<\/p>\n\n\n\n
      Syntax:<\/h2>
      try :\n    statements\nexcept:\n    statements\nfinally:\n    statements\n<\/pre><\/strong>\n<\/div><\/div>\n\n\n\n
      Let’s see an example–<\/strong><\/p>\n\n\n\n
      Example<\/h3>
      try:\n    a=10\n    b=0\n    c=4\n    print(a\/b)\nexcept ZeroDivisionError:\n    print('Tried to divide the number by zero')\nelse:\n    print('No exception found.. Entered else part')\nfinally:\n    print('Entered finally.. End of the program')\n<\/pre><\/strong>\n<\/div>
      Output<\/h3>
      Tried to divide the number by zero\nEntered finally.. End of the program<\/pre><\/strong><\/div><\/div>\n\n\n\n
      Explanation<\/strong><\/h3>\n\n\n\n
      The program starts with the try block<\/span><\/strong>, since the number is divided by zero<\/span><\/strong> it faces the exception<\/span><\/strong>. Due to the exception, it does not move to the else block<\/span><\/strong> but executes the finally block<\/span><\/strong>.<\/p>\n\n\n\n
      The Raise<\/strong> Keyword<\/h2>\n\n\n\n
      The built-in exceptions<\/span><\/strong> can be handled implicitly<\/span><\/strong>. But, Python also allows the user to trigger the exception i.e. the user can specify <\/span><\/strong>at what condition <\/span><\/strong>of the block the exception must be carried out.<\/p>\n\n\n\n
      Syntax:<\/h2>
      try:\n    condition\n    raise exception\n        statements\nexcept Exception:\n        statements\n<\/pre><\/strong>\n<\/div><\/div>\n\n\n\n
      Let’s see an example–<\/strong><\/p>\n\n\n\n
      Example<\/h3>
      try:\n    a=10\n    b=-2\n    if b<0:\n        raise ValueError\n    else:\n        print(a\/b)\nexcept ValueError:\n    print(' Don\u2019t divide by negative number... it will give negative result')<\/pre><\/strong>\n<\/div>
      Output<\/h3>
      Don\u2019t divide by negative number... it will give negative result<\/pre><\/strong><\/div><\/div>\n\n\n\n
      Explanation<\/strong><\/h3>\n\n\n\n
      In general, the value error<\/span><\/strong> occurs the object created to store the value does not exist<\/span><\/strong> or fails to store<\/span><\/strong> the value, but in this code, the ValueError <\/span><\/strong>is triggered <\/span><\/strong>when the value of b<\/span><\/strong> is negative<\/span><\/strong>.<\/p>\n\n\n\n
      Printing the errors<\/h2>\n\n\n\n
      If we don't know the error type<\/span><\/strong> and want to know the error then we can use as <\/span><\/strong>keyword to print the error.<\/p>\n\n\n\n
      Syntax:<\/h2>
      try:\n    # some code\nexcept Exception as e:\n    print(e)\n<\/pre><\/strong>\n<\/div><\/div>\n\n\n\n
      Now let's see some examples--<\/strong><\/p>\n\n\n\n
      Example<\/h3>
      try:\n  print(12\/0)\nexcept Exception as e:\n  print(e)\n<\/pre><\/strong>\n<\/div>
      Output<\/h3>
      division by zero<\/pre><\/strong><\/div><\/div>\n\n\n\n
      Explanation<\/strong><\/h3>\n\n\n\n
      In the second line, print(12\/0)<\/mark><\/strong> will give an error so, the program execution goes to except block where we first catch <\/mark><\/strong>the error using as <\/mark><\/strong>keyword and stored the error in the e <\/mark><\/strong>variable, then we simply printed <\/mark><\/strong>the e<\/mark><\/strong>.<\/p>\n\n\n\n
      Now, what if we have not used try... except... blocks, let's see--<\/strong><\/p>\n\n\n\n
      Example<\/h3>
      print(12\/0)\n<\/pre><\/strong>\n<\/div>
      Output<\/h3>
      Traceback (most recent call last):\n  File \"\/tmp\/sessions\/cc324f5c8863ef98\/main.py\", line 1, in \n    print(12\/0)\nZeroDivisionError: division by zero<\/pre><\/strong><\/div><\/div>\n\n\n\n
      Explanation<\/strong><\/h3>\n\n\n\n
      Here, we have tried to print the value which will occur due to 12\/0<\/mark><\/strong> which is an error<\/mark><\/strong> obviously, and the program terminates <\/mark><\/strong>with an error, while in the above example, we have printed <\/mark><\/strong>the error by using try-except<\/mark><\/strong> block and as keyword<\/mark><\/strong>.<\/p>\n\n\n\n
      \n
      Previous-- Python JSON<\/a><\/div>\n\n\n\n
      Next-- Python Regular Expressions<\/a><\/div>\n<\/div>\n\n\n\n
      \n","protected":false},"excerpt":{"rendered":"
      Definition Exception Handling In Python is one of the features of OOPS. It is mainly designed to handle runtime errors and the exceptions that corrupt…<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":833,"menu_order":22,"comment_status":"closed","ping_status":"closed","template":"template-s1-c-page.php","meta":{"footnotes":""},"class_list":["post-2791","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/copyassignment.com\/wp-json\/wp\/v2\/pages\/2791","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/copyassignment.com\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/copyassignment.com\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/copyassignment.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/copyassignment.com\/wp-json\/wp\/v2\/comments?post=2791"}],"version-history":[{"count":0,"href":"https:\/\/copyassignment.com\/wp-json\/wp\/v2\/pages\/2791\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/copyassignment.com\/wp-json\/wp\/v2\/pages\/833"}],"wp:attachment":[{"href":"https:\/\/copyassignment.com\/wp-json\/wp\/v2\/media?parent=2791"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}