Python File Open Error Checking
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you have probably seen some. There are (at least) two distinguishable kinds of errors: syntax errors and exceptions. 8.1. Syntax Errors¶ Syntax errors, also known as parsing errors, are perhaps the most common kind of python exception message complaint you get while you are still learning Python: >>> while True print('Hello world') File
Python Raise Custom Exception
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Python Print Exception
the function print(), since a colon (':') is missing before it. File name and line number are printed so you know where to look in case the input came from a script. 8.2. Exceptions¶ Even if a statement or expression is syntactically correct, it may cause an error when an attempt is made to execute it. Errors detected during execution are called exceptions and are not unconditionally fatal: you will soon is nested try block possible in python learn how to handle them in Python programs. Most exceptions are not handled by programs, however, and result in error messages as shown here: >>> 10 * (1/0) Traceback (most recent call last): File "
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us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is an exception can be in python a community of 6.2 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up Python's “open()” throws different errors for “file not found” - how to handle both https://docs.python.org/3/tutorial/errors.html exceptions? up vote 29 down vote favorite 6 I have a script where a user is prompted to type a filename (of a file that is to be opened), and if the file doesn't exist in the current directory, the user is prompted again. Here is the short version: file = input("Type filename: ") ... try: fileContent = open(filename, "r") ... except FileNotFoundError: ... When I tested my script on http://stackoverflow.com/questions/15032108/pythons-open-throws-different-errors-for-file-not-found-how-to-handle-b my MacOS X in Python 3.3x it worked perfectly fine when I type the wrong filename on purpose (it executes the suite under "expect"). However, when I wanted to run my code on a Windows computer in Python 3.2x, I get an error that says that "FileNotFoundError" is not defined. So, Python 3.2 on Windows thinks "FileNotFoundError" is a variable and the programs quits with an error. I figured out that Python 3.2 on Windows throws an "IOError" if the input filename is not valid. I tested it on my Linux machine in Python 2.7, and it's also an IOError. My problem is now, that the code with except "FileNotFoundError": won't run on Windows's Python 3.2, but if I change it to except "IOError": it won't work on my Mac anymore. How could I work around it? The only way I can think of is to use just except, which I usually don't want. python python-3.x filenotfoundexception ioerror share|improve this question edited Feb 22 '13 at 19:57 asked Feb 22 '13 at 19:48 user2015601 6 This isn't due to Mac/Windows, it's the version of Python. I would investigate 3.2/3.3 on OS X as well (and 3.3 on Windows), consult the change logs, and then revise the que
Working with File Objects 6.2.1. Reading Files 6.2.2. Closing Files 6.2.3. Handling I/O Errors 6.2.4. Writing to Files 6.3. Iterating http://www.diveintopython.net/file_handling/ with for Loops 6.4. Using sys.modules 6.5. Working with Directories 6.6. Putting It All Together 6.7. Summary In this chapter, you will dive into exceptions, file objects, http://www.python-course.eu/exception_handling.php for loops, and the os and sys modules. If you've used exceptions in another programming language, you can skim the first section to get a sense of in python Python's syntax. Be sure to tune in again for file handling. 6.1.Handling Exceptions 6.1.1. Using Exceptions For Other Purposes Like many other programming languages, Python has exception handling via try...except blocks. Python uses try...except to handle exceptions and raise to generate them. Java and C++ use try...catch to handle exceptions, and throw to generate python file open them. Exceptions are everywhere in Python. Virtually every module in the standard Python library uses them, and Python itself will raise them in a lot of different circumstances. You've already seen them repeatedly throughout this book. Accessing a non-existent dictionary key will raise a KeyError exception. Searching a list for a non-existent value will raise a ValueError exception. Calling a non-existent method will raise an AttributeError exception. Referencing a non-existent variable will raise a NameError exception. Mixing datatypes without coercion will raise a TypeError exception. In each of these cases, you were simply playing around in the Python IDE: an error occurred, the exception was printed (depending on your IDE, perhaps in an intentionally jarring shade of red), and that was that. This is called an unhandled exception. When the exception was raised, there was no code to explicitly notice it and deal with it, so it bubbled its way back to the default behavior built in to Python, w
and VariablesOperatorsinput and raw_input via the keyboardConditional StatementsWhile LoopsFor LoopsFormatted outputOutput with PrintSequential Data TypesDictionariesSets and Frozen SetsShallow and Deep CopyFunctionsRecursion and Recursive FunctionsTests, DocTests, UnitTestsMemoization with DecoratorsPassing ArgumentsNamespacesGlobal vs. Local VariablesFile ManagementModular Programming and ModulesIntroduction in Regular ExpressionsRegular Expressions, AdvancedLambda Operator, Filter, Reduce and MapList ComprehensionGeneratorsException HandlingObject Oriented ProgrammingInheritance ExampleSlotsClasses and Class CreationRoad to MetaclassesMetaclassesMetaclass Example: Count Function Calls Exception from the Rule "There are two great rules of life, the one general and the other particular. The first is that everyone can in the end, get what he wants, if he only tries. That is the general rule. The particular rule is that every individual is, more or less, an exception to the rule." Samuel Butler Delicate Handling "The finest qualities of our nature, like the bloom on fruits, can be preserved only by the most delicate handling. Yet we do not treat ourselves nor one another thus tenderly." Henry David Thoreau Supported by: Python Training Courses in Canada This topic in German / Deutsche Übersetzung: AusnahmebehandlungPython 2.7This tutorial deals with Python Version 2.7This chapter from our course is available in a version for Python3: Exception HandlingClassroom Training Courses This website contains a free and extensive online tutorial by Bernd Klein. If you are interested in an instructor-led classroom training in Canada or the US, you may have a look at the Python courses by Bernd Klein at Bodenseo © kabliczech - Fotolia.com Overview of Python courses by Bernd Klein. The Truth in Errors "The first step towards amendment is the recognition of error." Seneca "The world always makes the assumption that the exposure of an error is identical with the discovery of truth - that th