Python File Error Exception
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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 complaint you get python exceptions list while you are still learning Python: >>> while True print('Hello world') File "
Python Exception Message
while True print('Hello world') ^ SyntaxError: invalid syntax The parser repeats the offending line and displays a little ‘arrow' pointing at the earliest
Python Custom Exception
point in the line where the error was detected. The error is caused by (or at least detected at) the token preceding the arrow: in the example, the error is detected at the function print(), since
Python Raise Valueerror
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 learn how to handle them in Python programs. python filenotfounderror 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 "
a try statement with an except clause that mentions a particular class, that clause also handles any exception classes derived python programming can handle every error implicitly a) true b) false from that class (but not exception classes from which it is derived). python exception stack trace Two exception classes that are not related via subclassing are never equivalent, even if they have the same python print exception name. The built-in exceptions listed below can be generated by the interpreter or built-in functions. Except where mentioned, they have an "associated value" indicating the detailed cause of the https://docs.python.org/3/tutorial/errors.html error. This may be a string or a tuple of several items of information (e.g., an error code and a string explaining the code). The associated value is usually passed as arguments to the exception class's constructor. User code can raise built-in exceptions. This can be used to test an exception handler or to report an error condition "just https://docs.python.org/3/library/exceptions.html like" the situation in which the interpreter raises the same exception; but beware that there is nothing to prevent user code from raising an inappropriate error. The built-in exception classes can be subclassed to define new exceptions; programmers are encouraged to derive new exceptions from the Exception class or one of its subclasses, and not from BaseException. More information on defining exceptions is available in the Python Tutorial under User-defined Exceptions. When raising (or re-raising) an exception in an except or finally clause __context__ is automatically set to the last exception caught; if the new exception is not handled the traceback that is eventually displayed will include the originating exception(s) and the final exception. When raising a new exception (rather than using a bare raise to re-raise the exception currently being handled), the implicit exception context can be supplemented with an explicit cause by using from with raise: raise new_exc from original_exc The expression following from must be an exception or None. It will be
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 http://stackoverflow.com/questions/15032108/pythons-open-throws-different-errors-for-file-not-found-how-to-handle-b Learn more about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation http://www.diveintopython.net/file_handling/ Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is 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 exceptions? up vote 29 down vote favorite 6 I have python exception 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 my MacOS X in Python 3.3x it worked perfectly fine when I type the wrong python file error 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 question/title as appropriate. –user166390 Feb 22 '13 at 19:53 add a comment| 4 Answers 4 active oldest votes up vote 38 down vote accepted In 3.3, IOError became an alias for OSErro
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 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, 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 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 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, which is to spit out some debugging information and give up. In the IDE, that's no big deal, but if that happened