Error Handling Python 3
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Pages Local Site Map ------------------------ Rename Page Delete Page ------------------------ ------------------------ Remove Spam Revert to this revision ------------------------ SlideShow User Login Handling Exceptions The simplest way to handle exceptions is with a "try-except" block: 1 (x,y) = (5,0) 2 try: 3 z = x/y 4 except ZeroDivisionError: 5 print "divide by zero" python 3 print exception If you wanted to examine the exception from code, you could have: 1 (x,y)
Python Exception Args
= (5,0) 2 try: 3 z = x/y 4 except ZeroDivisionError as e: 5 z = e # representation: " at 0x817426c>" 6 print z # output: "integer division or modulo by zero" General Error Catching Sometimes, you want to catch all errors that could possibly be generated, but usually you don't.In most cases, you want to be as specific as possible (CatchWhatYouCanHandle). In the first example above, if you were using a catch-all exception clause and a user presses Ctrl-C, generating a KeyboardInterrupt, you don't want the program to print "divide by zero". However, there are some situations where it's best to catch all errors. For example, suppose you are writing an extension module to a web service. You want the error information to error handling in python script output the output web page, and the server to continue to run, if at all possible. But you have no idea what kind of errors you might have put in your code. In situations like these, you may want to code something like this: 1 import sys 2 try: 3 untrusted.execute() 4 except: # catch *all* exceptions 5 e = sys.exc_info()[0] 6 write_to_page( " Error: %sPython3 Exception Message
Try Except Finally Python 3
Data Types: Lists and StringsList ManipulationsShallow and Deep CopyDictionariesSets and Frozen Setsinput via the keyboardConditional StatementsLoops, python error handling best practices while LoopFor LoopsOutput with PrintFormatted output with string python error handling loop modulo and the format methodFunctionsRecursion and Recursive FunctionsParameter Passing in FunctionsNamespacesGlobal and Local python error handling index out of range VariablesDecoratorsMemoization with DecoratorsRead and Write FilesModular Programming and ModulesRegular ExpressionsRegular Expressions, AdvancedLambda Operator, Filter, Reduce and MapList ComprehensionIterators and GeneratorsException HandlingTests, https://wiki.python.org/moin/HandlingExceptions DocTests, UnitTestsObject Oriented ProgrammingClass and Instance AttributesProperties vs. getters and settersInheritanceMultiple InheritanceMagic Methods and Operator OverloadingOOP, Inheritance ExampleSlotsClasses and Class CreationRoad to MetaclassesMetaclassesMetaclass Use Case: Count Function Calls Exceptions "Nothing travels faster than the speed of light with the possible exception of http://www.python-course.eu/python3_exception_handling.php bad news, which obeys its own special laws." (Douglas Adams) "General principles should not be based on exceptional cases." (Robert J. Sawyer) This website is supported by: Linux and Python Training Courses This topic in German / Deutsche Übersetzung: AusnahmebehandlungPython 3This is a tutorial in Python3, but this chapter of our course is available in a version for Python 2.x as well: Exception Handling in Python 2.x Training Classes This website aims at providing you with educational material suitable for self-learning. Nevertheless, it is faster and more efficient to attend a "real" Python course in a classroo, with an experienced trainer. So why not attend one of the live Python courses in Strasbourg, Paris, London, Berlin, Munich, Hamburg, Frankfurt, or Lake Constance by Bernd Kle
motivate you to write clean, readable and efficient code in Python. Python has many built-in exceptionswhich forces your program to output an error when something in it goes wrong. http://www.programiz.com/python-programming/exception-handling When these exceptions occur, it causes the current process to stop and passes it to the calling process until it is handled. If not handled, our program will crash. For example, if function A calls function B http://stackoverflow.com/questions/11285313/try-except-as-error-in-python-2-5-python-3-x which in turn calls function C and an exception occurs in function C. If it is not handled in C, the exception passes to B and then to A. If never handled, an error message is error handling spit out and our program come to a sudden, unexpected halt. Catching Exceptions in Python In Python, exceptions can be handled using a try statement. A critical operation which can raise exception is placed inside the try clause and the code that handles exception is written in except clause. It is up to us, what operations we perform once we have caught the exception. Here is a simple example. # import module sys to python error handling get the type of exception import sys randomList = ['a', 0, 2] for entry in randomList: try: print("The entry is", entry) r = 1/int(entry) break except: print("Oops!",sys.exc_info()[0],"occured.") print("Next entry.") print() print("The reciprocal of",entry,"is",r) Output The entry is a Oops!
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up try … except … as error in Python 2.5 - Python 3.x up vote 20 down vote favorite 6 I want to keep & use the error value of an exception in both Python 2.5, 2.7 and 3.2. In Python 2.5 and 2.7 (but not 3.x), this works: try: print(10 * (1/0)) except ZeroDivisionError, error: # old skool print("Yep, error caught:", error) In Python 2.7 and 3.2 (but not in 2.5), this works: try: print(10 * (1/0)) except (ZeroDivisionError) as error: # 'as' is needed by Python 3 print("Yep, error caught:", error) Is there any code for this purpose that works in both 2.5, 2.7 and 3.2? Thanks python exception try-catch share|improve this question edited Jul 1 '12 at 20:30 Lion 9,618135385 asked Jul 1 '12 at 20:17 user1492917 304139 Can you not upgrade your 2.5 code to at least 2.7 and preferably 3? –Ben Jul 1 '12 at 20:35 except (ZeroDivisionError) as error: works fine in python 2.7 ideone.com/KfHBs –Ashwini Chaudhary Jul 1 '12 at 20:35 2 Python 3 is expressly not backwards compatible. Why restrict yourself to a limited subset of syntax that both languages support? –Cameron Jul 1 '12 at 20:40 @Ben (and Cameron) The code is used on appliances (often with Python 2.5) and on Linux installation (with Python 3.x on the horizon). Therefore both 2.5 and 3.x should work .... If I must choose, it will be 2.x code; that will work on on all installations: appliances and Linux installations. –user1492917 Jul 1 '12 at 20:48 2 @AshwiniChaudhary Indeed. That's what I already said in my post. Python 2.7 looks like a fine hybrid: accepting both 2.x and 3.x style python code. It's about 2.5 versus 3.x ... –user1492917 Jul 1 '12 at 20:49 | show 1 more comment 1 Answer 1 active oldest votes up vote 30 down vote accepted You can use one code base on Pythons 2.