Python Error Types
The second form of the constructor sets the corresponding attributes, described below. This applies only to unqualified names. exception UnicodeWarning¶ Base class for warnings related to Unicode. KeyErrorRaised when the specified key is not found in the dictionary. this contact form
New in version 2.5. up vote 64 down vote favorite 24 I have a function called by the main program: try: someFunction() except: print "exception happened!" but in the middle of the execution of the exception AssertionError¶ Raised when an assert statement fails. All Rights Reserved.
Python Custom Exception
Navigation index modules | next | previous | PyMOTW » Built-in Objects » View the discussion thread.blog comments powered by Disqus © Copyright Doug Hellmann. | | Last updated on Sep Warnings¶ The following exceptions are used as warning categories; see the warnings module for more information. raise NameError('HiThere') ... SyntaxErrorRaised when there is an error in Python syntax.
print 'My exception occurred, value:', e.value ... Raised when Python interpreter is quit by using the sys.exit() function. Because of the lack of standardization of floating point exception handling in C, most floating point operations also aren't checked. Python Exception Class Methods This means you cannot use it as a global variable in the function before assigning it.
The interpreter does not raise this exception itself very often, but some user code does. result = x / y ... try: print eval('five times three') except SyntaxError, err: print 'Syntax error %s (%s-%s): %s' % \ (err.filename, err.lineno, err.offset, err.text) print err $ python exceptions_SyntaxError.py Syntax error
User-defined Exceptions 8.6. Python Errno All user-defined exceptions should use Exception as a base class. exception NameError¶ Raised when a local or global name is not found. def __init__(self, value): ...
- Syntax raise [Exception [, args [, traceback]]] Here, Exception is the type of exception (for example, NameError) and argument is a value for the exception argument.
- When creating a module that can raise several distinct errors, a common practice is to create a base class for exceptions defined by that module, and subclass that to create specific
- RuntimeError Raised when a generated error does not fall into any category.
- Join them; it only takes a minute: Sign up python: How do I know what type of exception occured?
- EnvironmentError¶ Base class for errors that come from outside of Python (the operating system, filesystem, etc.).
Python Exception Message
Here's a list of common errors that result in runtime error messages which will crash your program. 1) Forgetting to put a : at the end of an if, elif, https://docs.python.org/3/tutorial/errors.html ValueErrorRaised when the built-in function for a data type has the valid type of arguments, but the arguments have invalid values specified. Python Custom Exception That was no valid number. Python Raise Valueerror Your comment will be queued in Akismet!
Errors and Exceptions 8.1. weblink Built-in Exceptions¶ Exceptions should be class objects. The syntax of the try-finally statement is this − try: You do your operations here; ...................... IndexErrorRaised when an index is not found in a sequence. Python Filenotfounderror
print 1/0 $ python exceptions_ZeroDivisionError.py Traceback (most recent call last): File "exceptions_ZeroDivisionError.py", line 12, in
Built-in Types Next topic 7. Python Attributeerror Object Has No Attribute finally: ... For example: >>> def this_fails(): ...
ZeroDivisonErrorRaised when division or modulo by zero takes place for all numeric types.
Then if its type matches the exception named after the except keyword, the except clause is executed, and then execution continues after the try statement. exception SyntaxWarning¶ Base class for warnings about dubious syntax. Corresponds to errno ECONNRESET. Python 3 Exceptions The difference between the above and using just except: without any argument is twofold: A bare except: doesn't give you the exception object to inspect The exceptions SystemExit, KeyboardInterrupt and GeneratorExit
except Exception as inst: ... print(inst.args) # arguments stored in .args ... For example: for arg in sys.argv[1:]: try: f = open(arg, 'r') except IOError: print 'cannot open', arg else: print arg, 'has', len(f.readlines()), 'lines' f.close() The use of the else clause http://vealcine.com/python-exception/python-standard-error-types.php New in version 2.0.
After the except clause(s), you can include an else-clause. Like this: from traceback import print_exc class dazhuangcao(Exception): pass try: raise dazhuangcao("hi") except Exception, e: print 'type is:', e.__class__.__name__ print_exc() # print "exception happened!" You will get output like this: type ImportWarning Warn about problems importing a module. exception UnicodeError¶ Raised when a Unicode-related encoding or decoding error occurs.
IOErrorIOError Raised when an input/ output operation fails, such as the print statement or the open() function when trying to open a file that does not exist.Raised for operating system-related errors. The errno value maps the winerror value to corresponding errno.h values. exception UnicodeDecodeError¶ Raised when a Unicode-related error occurs during decoding. The associated value is a string giving details about the type mismatch.
exception BlockingIOError¶ Raised when an operation would block on an object (e.g. exception RuntimeError¶ Raised when an error is detected that doesn't fall in any of the other categories. finally: This would always be executed. ...................... def func(): print unknown_name func() $ python exceptions_NameError.py Traceback (most recent call last): File "exceptions_NameError.py", line 15, in
SystemExitRaised by the sys.exit() function. print("division by zero!") ... Table Of Contents 8. There are (at least) two distinguishable kinds of errors: syntax errors and exceptions. 8.1.
exception BaseException¶ The base class for all built-in exceptions.