Computer File Management

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Questions and Answers

What is the primary reason why files are used in programming?

To permanently store data in a non-volatile memory

What is the correct order of file operations in Python?

Open, Read/Write, Close

What type of file is used to store characters or strings?

Text Files

What is the main purpose of method overloading?

To allow different ways to call a method with different parameters Signup and view all the answers

What is the purpose of the 'Append' file permission?

To add data to the end of a file Signup and view all the answers

What happens when you try to read a file that does not exist with the 'Read' file permission?

An error is raised Signup and view all the answers

What is a requirement for method overloading?

Same method name but different parameters Signup and view all the answers

What is the purpose of the 'Write' file permission?

To overwrite existing data in a file Signup and view all the answers

What is the primary purpose of a constructor in a class?

To declare and initialize data members of a class Signup and view all the answers

What is the difference between 'Read' and 'Write' file permissions?

Read is used to read data, while Write is used to write data Signup and view all the answers

Which of the following statements about the init method is true?

It is called as soon as an object of a class is instantiated Signup and view all the answers

What is object-oriented programming?

A way of building the structure and elements of computer programs Signup and view all the answers

What type of file is used to store entire data in the form of bytes?

Binary Files Signup and view all the answers

What is the purpose of method signature?

To differentiate methods with the same name Signup and view all the answers

What is a characteristic of method overloading?

Same method name but different parameters Signup and view all the answers

What is a benefit of method overloading?

More flexibility in coding Signup and view all the answers

What is the purpose of the 'try' block in Python?

To test a block of code for errors Signup and view all the answers

What type of exception is raised when a function receives an argument that has the right type but an inappropriate value?

ValueError Signup and view all the answers

What is the purpose of the 'finally' block in Python?

To execute a block of code regardless of the result of the 'except' block Signup and view all the answers

What is an example of an invalid input in Python?

Number divided by zero Signup and view all the answers

Which statement about structured programming is false?

Data is accessible from one function to another. Signup and view all the answers

What is the purpose of the 'except' block in Python?

To handle errors that occur in the code Signup and view all the answers

What is the purpose of a constructor in a class?

To initialize the instance of the class. Signup and view all the answers

What type of exception is raised when Python cannot find a module?

ImportError Signup and view all the answers

What type of attribute in a class is used to access or modify the object state?

Instance methods. Signup and view all the answers

What is the purpose of the 'else' block in Python?

To execute a block of code if no errors were raised Signup and view all the answers

What is true about objects of the same class?

All instances of a class share the class variables. Signup and view all the answers

What type of exception is raised when a file cannot be opened?

IOError Signup and view all the answers

What is the limitation of structured programming?

Data is not accessible from one function to another. Signup and view all the answers

What is the characteristic of objects in a class?

Objects have both data and methods. Signup and view all the answers

What is the purpose of class methods?

To access and modify both class and instance variables. Signup and view all the answers

What is the characteristic of static variables?

Only one copy of the static variable will be created and shared between all objects of the class. Signup and view all the answers

What is the primary advantage of encapsulation in object-oriented programming?

Enhancing security of data by protecting it from unauthorized access Signup and view all the answers

What is the benefit of using getter and setter methods in encapsulation?

To hide the implementation of data modification from the user Signup and view all the answers

What is the main advantage of polymorphism in software design?

Allowing objects of different classes to be treated as objects of a common superclass Signup and view all the answers

What is the result of using encapsulation in object-oriented programming?

Improved security and data hiding Signup and view all the answers

What is the purpose of a getter method in encapsulation?

To retrieve the value of a data member Signup and view all the answers

What is a benefit of using polymorphism in software design?

Enabling flexibility and extensibility in software design Signup and view all the answers

What is the result of using polymorphism in software design?

Simplified maintenance of applications Signup and view all the answers

What is the purpose of a setter method in encapsulation?

To modify a data member Signup and view all the answers

Study Notes

File Operations

A file is a named location on disk to store program-related information.
Files are used to permanently store data in a non-volatile memory (e.g. Hard disk).
File operations in Python take place in the following order:
- Open a file
- Read or write (perform operation)
- Close the file
File types include:
- Text Files - used to store characters or strings
- Binary Files - store entire data in the form of bytes (i.e., a group of 8 bits each)

File Permissions

Read (r) - File can be 'looked at' by the program but not changed. Error if the file doesn't already exist.
Append (a) - File can be added to. File is created if it doesn't already exist.
Write (w) - Overwrites existing data, starting from the beginning of the file. File is created if it doesn't already exist.

Exception Handling

IOError - If the file cannot be opened.
ImportError - If Python cannot find the module.
ValueError - Raised when a function receives an argument that has the right type but an inappropriate value.
try - used to test a block of code for errors.
except - used to handle errors.
finally - used to execute blocks of code regardless of the result of try and except blocks.

Method Overloading

Definition: Defining multiple methods in the same scope (usually in the same class) with the same name but different signatures (number or type of parameters).
Purpose: To allow different ways to call a method with different parameters.

Object-Oriented Programming

A constructor is used to define and initialize data members of a class.
The primary purpose of a constructor is to declare and initialize data members of a class.
The init method is called when an object of a class is instantiated.
Method signature must have the same method name but different parameters (not directly supported in Python).
Object-Oriented Programming is a fundamental style of computer programming that allows building the structure and elements of computer programs.

Encapsulation

Advantages:
- Security: Protects an object from unauthorized access.
- Data Hiding: The user does not know what is going on behind the scene.
- Allows private and protected access levels to prevent accidental data modification.

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