Python Runtime Error Valueerror
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This module never needs to be imported explicitly: the exceptions are provided in the built-in namespace as well as the exceptions module. For class exceptions, valueerror python in a try statement with an except clause that mentions python valueerror example a particular class, that clause also handles any exception classes derived from that class (but not exception classes from python filenotfounderror which it is derived). Two exception classes that are not related via subclassing are never equivalent, even if they have the same name. The built-in exceptions listed below can be
Python Custom Exception
generated by the interpreter or built-in functions. Except where mentioned, they have an "associated value" indicating the detailed cause of the error. This may be a string or a tuple containing several items of information (e.g., an error code and a string explaining the code). The associated value is the second argument to the raise statement. If the exception python exception message class is derived from the standard root class BaseException, the associated value is present as the exception instance's args attribute. User code can raise built-in exceptions. This can be used to test an exception handler or to report an error condition "just 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. The following exceptions are only used as base classes for other exceptions. exception BaseException¶ The base class for all built-in exceptions. It is not meant to be directly inherited by user-defined classes (for that, use Exception). If str() or unicode() is called on an instance of this class, the representation of the argument(s) to the instance are returned, or
Exception StandardError ArithmeticError LookupError EnvironmentError Raised Exceptions AssertionError AttributeError EOFError FloatingPointError GeneratorExit IOError ImportError IndexError KeyError KeyboardInterrupt python exception class methods MemoryError NameError NotImplementedError OSError OverflowError ReferenceError RuntimeError StopIteration SyntaxError SystemError SystemExit
Python Errno
TypeError UnboundLocalError UnicodeError ValueError ZeroDivisionError Warning Categories Navigation Table of Contents Previous: Built-in Objects Next: String
Python Attributeerror Object Has No Attribute
Services This Page Show Source Examples The output from all the example programs from PyMOTW has been generated with Python 2.7.8, unless otherwise noted. Some of the features https://docs.python.org/2/library/exceptions.html described here may not be available in earlier versions of Python. If you are looking for examples that work under Python 3, please refer to the PyMOTW-3 section of the site. Navigation index modules | next | previous | PyMOTW » Built-in Objects » exceptions - Built-in error classes¶ Purpose:The exceptions module defines the built-in https://pymotw.com/2/exceptions/ errors used throughout the standard library and by the interpreter. Available In:1.5 and later Description¶ In the past, Python has supported simple string messages as exceptions as well as classes. Since 1.5, all of the standard library modules use classes for exceptions. Starting with Python 2.5, string exceptions result in a DeprecationWarning, and support for string exceptions will be removed in the future. Base Classes¶ The exception classes are defined in a hierarchy, described in the standard library documentation. In addition to the obvious organizational benefits, exception inheritance is useful because related exceptions can be caught by catching their base class. In most cases, these base classes are not intended to be raised directly. BaseException¶ Base class for all exceptions. Implements logic for creating a string representation of the exception using str() from the arguments passed to the constructor. Exception¶ Base class for exceptions that do not result in quitting the running application. All user-defined exceptions should use Exception as a base cl
learning the language. 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 http://inventwithpython.com/blog/2012/07/09/16-common-python-runtime-errors/ of an if, elif, else, for, while, class, or def statement. (Causes “SyntaxError: invalid https://python-textbok.readthedocs.io/en/latest/Errors_and_Exceptions.html syntax”) This error happens with code like this: if spam == 42 print('Hello!') 2) Using = instead of ==. (Causes “SyntaxError: invalid syntax”) The = is the assignment operator while == is the "is equal to" comparison operator. This error happens with code like this: if spam = 42: print('Hello!') 3) python exception Using the wrong amount of indentation. (Causes “IndentationError: unexpected indent” and “IndentationError: unindent does not match any outer indentation level” and “IndentationError: expected an indented block”) Remember that the indentation only increases after a statement ending with a : colon, and afterwards must return to the previous indentation. This error happens with code like this: print('Hello!') print('Howdy!') ...and this: if spam == 42: print('Hello!') print('Howdy!') ...and this: if python runtime error spam == 42: print('Hello!') 4) Forgetting the len() call in a for loop statement. (Causes “TypeError: 'list' object cannot be interpreted as an integer”) Commonly you want to iterate over the indexes of items in a list or string, which requires calling the range() function. Just remember to pass the return value of len(someList), instead of passing just someList. This error happens with code like this: spam = ['cat', 'dog', 'mouse'] for i in range(spam): print(spam[i]) (Update: As a few have pointed out, what you might need is just for i in spam: rather than the above code. But the above is for the very legitimate case where you need the index in the body of the loop, rather than just the value itself.) 5) Trying to modify a string value. (Causes “TypeError: 'str' object does not support item assignment”) Strings are an immutable data type. This error happens with code like this: spam = 'I have a pet cat.' spam[13] = 'r' print(spam) What you probably want is this: spam = 'I have a pet cat.' spam = spam[:13] + 'r' + spam[14:] print(spam) 6) Trying to concatenate a non-string value to a string value. (Causes
Handling exceptions The try and except statements How an exception is handled Error checks vs exception handling The else and finally statements Exercise 2 The with statement Using the exception object Raising exceptions Exercise 3 Debugging programs Debugging tools Pyflakes, pylint, PyChecker and pep8 pdb Logging Exercise 4 Answers to exercises Answer to exercise 1 Answer to exercise 2 Answer to exercise 3 Answer to exercise 4 Functions Classes Object-oriented programming Packaging and testing Useful modules in the Standard Library Introduction to GUI programming with tkinter Sorting, searching and algorithm analysis Object-Oriented Programming in Python Docs » Errors and exceptions Edit on Bitbucket Errors and exceptions¶ Errors¶ Errors or mistakes in a program are often referred to as bugs. They are almost always the fault of the programmer. The process of finding and eliminating errors is called debugging. Errors can be classified into three major groups: Syntax errors Runtime errors Logical errors Syntax errors¶ Python will find these kinds of errors when it tries to parse your program, and exit with an error message without running anything. Syntax errors are mistakes in the use of the Python language, and are analogous to spelling or grammar mistakes in a language like English: for example, the sentence Would you some tea? does not make sense - it is missing a verb. Common Python syntax errors include: leaving out a keyword putting a keyword in the wrong place leaving out a symbol, such as a colon, comma or brackets misspelling a keyword incorrect indentation empty block Note it is illegal for any block (like an if body, or the body of a function) to be left co