Found 10805 Articles for Python

This can be done by following codestry: x, y =7, 0 z = x/y except: passORtry: x, y =7, 0 z = x/y except Exception: passThese codes bypass the exception in the try statement and ignore the except clause and don’t raise any exception.The difference in the above codes is that the first one will also catch KeyboardInterrupt, SystemExit etc, which are derived directly from exceptions.BaseException, not exceptions.Exception.It is known that the last thrown exception is remembered in Python, some of the objects involved in the exception-throwing statement are kept live until the next exception. We might want to do ... Read More

It is possible to define multiple exceptions with the same except clause. It means that if the Python interpreter finds a matching exception, then it’ll execute the code written under except clause.In general, the syntax for multiple exceptions is as followsExcept(Exception1, Exception2, …ExceptionN) as e:When we define except clause in this way, we expect the same code to throw different exceptions. Also, we want to take the action in each case.Example codeimport sys try: d = 8 d = d + '5' except(TypeError, SyntaxError)as e: print sys.exc_info()We get output as shown(, TypeError("unsupported operand type(s) for  +: 'int' and 'str'", ), ... Read More

Here we are passing a variable to given exception. We are defining a custom exception ExampleException which is a subclass of base class Exception and also defining the __init__ method. We use a try-except block to raise the exception and pass the variable to the exception as follows.Exampleclass ExampleException(Exception): def __init__(self, foo): self.foo = foo try: raise ExampleException("Bar!") except ExampleException as e: print e.foo Output"C:/Users/TutorialsPoint1/~bar.py" Bar!

In given code, a custom exception FooException has been created which is a subclass of the super class Exception. We will pass a string object to the custom exception as followsExample#foobar.py class FooException(Exception): def __init__(self, text, *args): super ( FooException, self ).__init__ ( text, *args ) self.text = text try: bar = input("Enter a string:") if not isinstance(bar, basestring): raise FooException(bar) except FooException as r: print 'there is an error' else:       print type(bar) print barIf this script is run at the terminal as follows we get$ python foobar.pyWe get the following if we enter a stringOutput"C:/Users/TutorialsPoint1/~foobar.py" Enter ... Read More

A syntax error happens when Python can't understand what you are saying. A run-time error happens when Python understands what you are saying, but runs into trouble when following your instructions. This is called a run-time error because it occurs after the program starts running.A program or code may be syntactically correct and may not throw any syntax error. This code may still show error after it starts running.The given code can be corrected as followsa = input('Enter a number:') b = input('Enter a number:') c = a*b print cThe output we get is as follows"C:/Users/TutorialsPoint1/~.py" Enter a number:7 Enter ... Read More

We catch multiple exceptions in one except block as followsAn except clause may name multiple exceptions as a parenthesized tuple, for exampletry: raise_certain_errors(): except (CertainError1, CertainError2, …) as e: handle_error()Separating the exception from the variable with a comma still works in Python 2.6 and 2.7, but is now deprecated and does not work in Python 3; now we should use ‘as’.The parentheses are necessary as the commas are used to assign the error objects to names. The ‘as’ keyword is for the assignment. We can use any name for the error object like ‘error’, ‘e’, or ‘err’Given code can be ... Read More

A substring is a contiguous sequence of characters within a string. In other words, it's a smaller piece of text that appears within a larger piece of text. For example, in the string "lorem ipsum", the substring "lorem" appears within the larger string. Similarly, the substring "em i" appears within the larger string "lorem ipsum" as well. Substring operations are common in programming and can be used for various tasks such as searching for a specific word in a text, extracting parts of a text, or replacing certain parts of a text with other words. Checking if a substring is ... Read More

A KeyError is raised when a value is not found as a key of a dictionary. The given code is rewritten as follows to catch the exception and find its type.Exampleimport sys try: s = {'a':5, 'b':7}['c'] except: print (sys.exc_info())Output(, KeyError('c',), )

The assert statement has the following syntax.assert , The line above is read as: If evaluates to False, an exception is raised and will be output.If we want to test some code block or an expression we put it after an assert keyword. If the test passes or the expression evaluates to true nothing happens. But if the test fails or the expression evaluates to false, an AssertionError is raised and the message is printed out or evaluated.Assert statement is used for catching/testing user-defined constraints. It is used for debugging code and is inserted at the start of ... Read More

In exception handling in Python, we use the try and except statements to catch and handle exceptions. The code within the try clause is executed statement by statement.If an exception occurs, the rest of the try block is skipped and the except clause is executed.Exampletry: 'apple' + 6 except Exception: print "Cannot concatenate 'str' and 'int' objects"OutputCannot concatenate 'str' and 'int' objectsWe avoid the traceback error message elegantly with a simple message like above by using try except statements for exception handling.In addition to using an except block after the try block, we can also use the finally block. The ... Read More