Exception Handling in Python
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What happens when the runtime system cannot find an appropriate exception after searching all the methods in the call stack?

  • The program prints a warning message and continues execution.
  • The program continues to execute normally, ignoring the exception.
  • The program execution stops. (correct)
  • The exception is passed to the operating system for handling.

In Python, what is the purpose of the try block when handling exceptions?

  • It defines a block of code where exceptions are generated.
  • It defines a block of code that should always be executed, regardless of whether an exception occurs.
  • It defines a block of code that is executed if a specific exception is caught.
  • It defines a block of code where potential exceptions might occur, and if they do, control is transferred to the `except` block. (correct)

What is the purpose of the except block in Python exception handling?

  • It defines a block of code that is executed only if an exception is caught. (correct)
  • It defines a block of code that is executed unconditionally after the `try` block.
  • It defines a block of code that generates specific exceptions.
  • It defines a block of code that is executed only if no exception is caught.

Regarding exception handling in Python, what does the statement "An exception is said to be caught when a code that is designed to handle a particular exception is executed" mean?

<p>An exception is caught when the program's error handling mechanism successfully identifies and processes the exception. (B)</p> Signup and view all the answers

Why is it important to place code that is likely to throw an exception within a try block?

<p>It prevents the program from crashing and allows for graceful handling of unexpected events. (A)</p> Signup and view all the answers

What is the primary purpose of exception handlers?

<p>To execute code when a specific error occurs during program execution. (A)</p> Signup and view all the answers

Which of the following statements are true about the 'raise' statement in Python?

<p>It allows programmers to explicitly trigger exceptions during program execution. (B)</p> Signup and view all the answers

How does the 'raise' statement function when an exception is thrown in Python?

<p>It immediately transfers control to the nearest 'try...except' block that handles the raised exception. (B)</p> Signup and view all the answers

What is the primary difference between a built-in exception and a user-defined exception in Python?

<p>User-defined exceptions allow programmers to create custom error types for more specific error handling. (C)</p> Signup and view all the answers

What is the purpose of providing an optional argument within the 'raise' statement in Python?

<p>To specify the error message associated with the raised exception. (B)</p> Signup and view all the answers

What happens to the code execution flow when an exception is raised in Python?

<p>The execution of the current code block is terminated, and control is transferred to an appropriate exception handler. (C)</p> Signup and view all the answers

In the code snippet provided, what type of exception would be raised if the value of 'length' is greater than the length of the list 'numbers'?

<p>IndexError (B)</p> Signup and view all the answers

Why won't the message 'NO EXECUTION' be displayed in the code snippet provided in Figure 1.6?

<p>The 'IndexError' exception prevents the code following the 'raise' statement from executing. (B)</p> Signup and view all the answers

What will happen if a non-zero value is inputted for the denominator in Program 1-2?

<p>The quotient will be calculated and displayed. (D)</p> Signup and view all the answers

Which error is specifically handled in the except clause of Program 1-2?

<p>ZeroDivisionError (A)</p> Signup and view all the answers

What message is printed if the user enters zero as the denominator?

<p>Denominator as Zero….not allowed (D)</p> Signup and view all the answers

What is printed after the try..except block, regardless of whether an exception occurs?

<p>OUTSIDE try..except block (D)</p> Signup and view all the answers

How is the control flow affected when the except clause is triggered?

<p>Control shifts to the except block for error handling. (A)</p> Signup and view all the answers

In the context of exception handling, what does the try block contain?

<p>Program statements that may cause exceptions. (A)</p> Signup and view all the answers

What is the primary purpose of the except clause in the context of the try..except structure?

<p>To handle specific exceptions when they arise. (B)</p> Signup and view all the answers

What happens when an exception is raised in a try block?

<p>The program searches for a matching except block. (B)</p> Signup and view all the answers

Why is it necessary to have multiple except blocks?

<p>To perform different actions based on different exceptions. (D)</p> Signup and view all the answers

What will be outputted if the denominator entered is zero?

<p>Denominator as ZERO is not allowed (D)</p> Signup and view all the answers

What type of exception does the program handle if a non-integer is entered as the denominator?

<p>ValueError (C)</p> Signup and view all the answers

When will the message 'OUTSIDE try..except block' be displayed?

<p>When the try block is executed without exceptions. (D)</p> Signup and view all the answers

If no matching except block is found for a raised exception, what occurs?

<p>The program terminates. (D)</p> Signup and view all the answers

Which of the following is NOT a reason for using exception handling in Python?

<p>To allow retrying the same code after an error. (D)</p> Signup and view all the answers

What is the role of the try block in exception handling?

<p>To execute a block of code that may raise an exception. (C)</p> Signup and view all the answers

What is the appropriate exception type to handle the case where the user inputs a non-integer value?

<p>TypeError (D)</p> Signup and view all the answers

Which exception type should be used to handle the case where the second number entered is zero, leading to division by zero?

<p>ZeroDivisionError (B)</p> Signup and view all the answers

What is the primary purpose of the 'else' block in the provided code snippet?

<p>To execute code when the 'try' block executes successfully (B)</p> Signup and view all the answers

Which of these statements best describes the purpose of the 'finally' block in Python exception handling?

<p>Executes regardless of whether an exception occurred or not. (C)</p> Signup and view all the answers

In Note 8, the text suggests using a specific exception type to handle the scenario of using an incorrect number of arguments for a method like 'sqrt()'. Which exception type should be used?

<p>TypeError (D)</p> Signup and view all the answers

What is the primary purpose of the try block in the provided code?

<p>To catch and handle any potential errors during division calculations. (B)</p> Signup and view all the answers

Flashcards

Program Termination

If the program encounters an error that cannot be handled, the program stops running.

Try Block

A block of code that attempts to execute potentially problematic code. It is followed by an 'except' block to handle exceptions.

Except Block

A block of code that is executed if an exception occurs within the corresponding 'try' block.

Exception Handling

The process of responding to an error or exceptional event during program execution.

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Catching an Exception

When the program encounters an error and it is identified and handled by the exception handling mechanism.

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Exception

An unexpected event that occurs during program execution, disrupting the normal flow of the program. It can be caused by various factors, such as invalid user input, file access errors, or network connection issues.

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Exception Handler

A special block of code that intercepts and handles exceptions, preventing the program from crashing. It takes action to recover from the unexpected situation, providing a more graceful and predictable way for the program to continue.

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Exception Type

A specific type of exception, such as 'ZeroDivisionError' or 'TypeError', indicating the nature of the error encountered. Each exception has a unique name that identifies it.

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Raise Statement

The statement used to explicitly raise or throw an exception in a program, allowing you to force an error condition for testing or to signal an unexpected event.

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Exception Message

A message associated with an exception, providing a description of the error that occurred. It typically includes details about the cause of the exception.

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Built-in Exception

A built-in exception provided by the programming language, representing common errors such as division by zero, invalid index access, or type mismatch.

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User-defined Exception

An exception created by the programmer to represent specific error conditions within their application. It's defined and used to handle custom scenarios.

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ZeroDivisionError

A specific type of exception that occurs when attempting to divide by zero.

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Normal execution flow

Code within a try block that is executed if no exceptions are raised.

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Exception handling code

The code within the except block that executes if a targeted exception is encountered within the corresponding try block.

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Try...except clause

The standard way to handle errors and prevent program crashes. It allows for graceful recovery from unexpected situations.

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Code after try-except block

The code that follows the try...except block, which is executed regardless of whether an exception was raised or handled.

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ValueError

A situation where an operation is attempted on data that does not have the correct type, resulting in an error.

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Multiple Except Blocks

Multiple 'except' blocks can be used after a single 'try' block to handle different types of errors.

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Exception Matching

When an exception arises, Python searches for a matching 'except' block to handle it. If no matching block is found, the program terminates.

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Finally Block

A code block that is always executed regardless of whether an exception occurred or not. Used to clean up resources or perform final actions.

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Try Block Purpose

The code within a 'try' block may raise exceptions during execution.

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Else Block

Executed only when no exception occurs within the corresponding 'try' block.

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Unhandled Exceptions

If the 'try' block encounters an exception that is not specifically handled by an 'except' block, the exception is re-raised after the 'finally' block executes.

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Control Transfer After Finally

Python code that executes after the 'finally' block is considered to be at the same level as the 'try' block.

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Integer Conversion

The function 'int()' is used to convert the input into an integer.

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Study Notes

Exception Handling in Python

  • Python programs can execute or behave abnormally due to various errors
  • Errors can be syntax errors, runtime errors, or logical errors
  • These errors disrupt the normal execution flow, and are called exceptions
  • The programmer can include appropriate code to handle such erroneous situations

Syntax Errors

  • Detected when rules of programming language are not followed
  • Also known as parsing errors
  • Interpreter stops execution if syntax error is encountered
  • Python displays error name and small description
  • Error dialog box or display in shell mode, will be displayed while working in script or shell mode
  • Python reports error with brief description and suggestion for fixing

Exceptions

  • Python object representing an error
  • Raised when an error occurs during program execution
  • Programmer handles exceptions to prevent abnormal termination of the program
  • Python interpreter creates an exception object that contains information about the error like type, file location, and position in the program. This object is then handled by the runtime system

Built-in Exceptions

  • Common errors, having standardized solutions
  • Example: SyntaxError, ValueError, IOError

Raising Exceptions

  • Programmers can forcefully raise exceptions using the raise statement.
  • Used for specific error conditions and helps with error handling rather than simply stopping execution.
  • Can use assert statement for testing expressions and triggering exceptions if they evaluate to false
  • Python's runtime system searches for a matching except block

Handling Exceptions

  • Exception handling involves additional code to handle errors
  • Using try...except statements. try block contains suspicious code, and except handles expected exceptions.
  • finally block always executes irrespective of exceptions
  • Exception handlers are designed to execute when a particular exception is raised

The try...except Block

  • try: block contains the code that might raise exceptions
  • except block contains the code that handles the exception
  • Multiple except clauses can handle different types of exceptions

The finally Block

  • Always executes whether or not an exception occurred.
  • Useful for clean up actions (e.g., closing files)

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Python Exception Handling PDF

Description

This quiz covers the concept of exception handling in Python, including types of errors such as syntax, runtime, and logical errors. Learn how to manage these exceptions to maintain the normal flow of your programs. It is essential for any Python programmer to understand these principles.

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