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Explain Try, Except and Else statement in Python.

I have the following code that throws an exception as follows , showing output as , How do I rewrite this code to use the else clause?
Rajendra Dharmkar
Answered on 6th Dec, 2017

The common method to handle exceptions in python is using the "try-except" block. We can even include an else clause after except clause. The statements in the else block are executed if there is no exception in the try statement.The optional else clause is executed if and when control flows ... Read More

Is there a standard way of using exception chains in Python 3?

The following code throws more than one exceptions , How to rewrite it to show exception chaining in python 3.x?
Rajendra Dharmkar
Answered on 6th Dec, 2017

During the handling of one exception ‘A’, it is possible that another exception ‘B’ may occur. In Python 2.0 versions, if this happens, exception B is propagated outward and exception A is lost. It is useful to know about both exceptions in order to debug the problem.Sometimes it is useful ... Read More

How do I manually throw/raise an exception in Python?

I have this code that can throw up an error. , How do I manually throw or raise an exception in the given code?
Rajendra Dharmkar
Answered on 6th Dec, 2017

We use the most specific exception constructor that fits our specific issue rather than raise generic exceptions. To catch our specific exception, we'll have to catch all other more specific exceptions that subclass it.We should raise specific exceptions and handle the same specific exceptions.To raise the specific exceptions we use ... Read More

What is the best way to log a Python exception?

In the code below , I want to log the exception. How do I do that?
Rajendra Dharmkar
Answered on 6th Dec, 2017

We import the logging module and then use the logging.exception method to create a log of the python exception.import logging try: print 'toy' + 6 except Exception as e: logging.exception("This is an exception log")We get the following outputERROR:root:This is an exception log Traceback (most recent call last): File "C:/Users/TutorialsPoint1/PycharmProjects/TProg/Exception handling/loggingerror1.py", ... Read More

How to declare custom exceptions in modern Python?

To declare a simple custom exception we can have a script like this , But how do I declare a custom exception to override something or to pass extra arguments to the exception?
Rajendra Dharmkar
Answered on 6th Dec, 2017

To override something or pass extra arguments to the exception we do like this in modern python:class ValidationError(Exception): def __init__(self, message, errors): super(ValidationError, self).__init__(message) self.errors = errorsThat way we could pass dictionary of error messages to the second parameter, and get to it later on when needed. Read More

Why are Python exceptions named "Error" (e.g. ZeroDivisionError, NameError, TypeError)?

Errors like syntax errors occurring at compile time are called errors and those occurring at runtime are called exceptions. Yet python exceptions like NameError, TypeError…have their nam.....
Rajendra Dharmkar
Answered on 6th Dec, 2017

We see that most exceptions have their names ending in word ‘error’ pointing that they are errors which is the meaning of exceptions anyway.Errors in restricted sense are taken to mean syntax errors in python and those errors occurring at run time are called exceptions. As we know that classes ... Read More

How to capture and print Python exception message?

I have code that can raise an exception , How do I catch the exception message?
Rajendra Dharmkar
Answered on 6th Dec, 2017

Python exception messages can be captured and printed in different ways as shown in two code examples below. In the first one, we use the message attribute of the exception object.try: a = 7/0 print float(a) except BaseException as e: print e.messageOUTPUTinteger division or modulo by zeroIn case of given ... Read More

How do you handle an exception thrown by an except clause in Python?

I have code where an except clause throws an exception. , How to handle this exception?
Rajendra Dharmkar
Answered on 6th Dec, 2017

We have a scenario in which code in except clause itself raises exception. In given code, we can handle the exception raised by except clause as follows.import sys try: a = john except: try: 4/0 except: print sys.exc_info() We get the following output"C:/Users/TutorialsPoint1/~.py" (<type 'exceptions.ZeroDivisionError'>, ZeroDivisionError('integer division or modulo ... Read More

How will you explain that an exception is an object in Python?

Here is code in which an exception is raised. , Is ‘err’ an exception object and what does sys.exc_info() do?
Rajendra Dharmkar
Answered on 6th Dec, 2017

Yes in given code ‘err’ is an exception object.In python everything is an object. And every object has attributes and methods. So exceptions much like lists, functions, tuples etc are also objects. So exceptions too have attributes like other objects. These attributes can be set and accessed as follows. There ... Read More

How to get Python exception text?

In python code, how do I access/get the python exception text or message or information like the filename and line number where the exception occurred?
Rajendra Dharmkar
Answered on 6th Dec, 2017

If a python code throws an exception, we can catch it and print the type, the error message, traceback and get information like file name and line number in python script where the exception occurred.We can find the type, value, traceback parameters of the errorType gives the type of exception ... Read More

Where can I find good reference document on python exceptions?

I am interested in mastering python exception handling. Can somebody suggest where I can find a good reference document on python exceptions?
Rajendra Dharmkar
Answered on 6th Dec, 2017

The following link is a  good reference document on python exceptionshttps://docs.python.org/2/library/exceptions.html

How to catch IOError Exception in Python?

If I run the following code, I am getting an error. , How to catch this error and know its type?
Rajendra Dharmkar
Answered on 6th Dec, 2017

IOError ExceptionIt is an error 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. It is also raised for operating system-related errors.If the given code is written in a try block, it raises an ... Read More

How to catch ArithmeticError Exception in Python?

If I run the following line of code, I am getting an error. , How to catch this error and know its type?
Rajendra Dharmkar
Answered on 6th Dec, 2017

ArithmeticError Exception is the base class for all errors that occur for numeric calculations. It is the base class for those built-in exceptions like: OverflowError, ZeroDivisionError, FloatingPointErrorWe can catch the exception in given code as followsimport sys try: 7/0 except ArithmeticError as e: print e print sys.exc_type print 'This is ... Read More

How to catch SyntaxError Exception in Python?

When I run the following line of code, I get error , How do I handle this exception and find its type?
codefoxx
Answered on 6th Dec, 2017

A SyntaxError occurs any time the parser finds source code it does not understand. This can be while importing a module, invoking exec, or calling eval(). Attributes of the exception can be used to find exactly what part of the input text caused the exception.We rewrite the given code to ... Read More

How to catch EOFError Exception in Python?

If I run this code at the terminal as follows , I get an error How do I catch this exception and know its type?
codefoxx
Answered on 6th Dec, 2017

An EOFError is raised when a built-in function like input() or raw_input() do not read any data before encountering the end of their input stream. The file methods like read() return an empty string at the end of the file.The given code is rewritten as follows to catch the EOFError ... Read More

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