Software Development - ITATCITO3 - Lecture 6
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What does the object represent in the context of behavior?

  • Methods and properties of a class
  • Attributes and states of an entity
  • Current state and behavior defined in the class of the object (correct)
  • Current state and past behaviors

    • Which component is NOT part of the object as defined in the context?

  • Interaction with other objects (correct)
  • Data encapsulated within the object
  • Behavior defined in the class of the object
  • Current state

    • Which of the following best describes the relationship between state and behavior in an object?

  • Behavior is completely independent of state
  • State influences behavior but is separate (correct)
  • State is determined by the behavior of the object
  • State and behavior are interchangeable concepts

    • In object-oriented programming, the term 'class' typically refers to:

    <p>A blueprint for creating objects, which includes current states</p> Signup and view all the answers

    How can the object’s behavior be influenced according to its current state?

    <p>Through methods that change the object's current state</p> Signup and view all the answers

    What defines the attributes of a class?

    <p>Member variables within the class body</p> Signup and view all the answers

    How is the behavior of objects represented in classes?

    <p>By the definition of methods</p> Signup and view all the answers

    Which of the following statements about member variables is true?

    <p>They are defined as variables within the body of the class.</p> Signup and view all the answers

    What is an example of modeling the behavior of a dog in a class?

    <p>Creating a method 'bark()' within the dog class</p> Signup and view all the answers

    Which of the following correctly differentiates attributes from methods in a class?

    <p>Attributes are variables in a class, while methods are functions that define its behavior.</p> Signup and view all the answers

    What type of variables are name and color in the class Cat?

    <p>Reference type</p> Signup and view all the answers

    Where are the references for name and color stored in the class Cat?

    <p>In the dynamic memory (heap)</p> Signup and view all the answers

    What is kept in the object itself for the variables name and color in the class Cat?

    <p>The addresses (pointers) of the strings</p> Signup and view all the answers

    Which of the following correctly describes how name and color are stored in class Cat?

    <p>Their references are stored in the object</p> Signup and view all the answers

    What is the primary difference between reference type and value type in the context of the class Cat?

    <p>Reference type stores a pointer to the data, while value type stores the data itself</p> Signup and view all the answers

    What range of numbers can the method Next(n) generate?

    <p>From 0 to n-1</p> Signup and view all the answers

    What value is guaranteed to be included in the output of Next(n)?

    <p>Zero</p> Signup and view all the answers

    Which statement is true about the value returned by Next(n)?

    <p>It can be zero.</p> Signup and view all the answers

    If n is set to 5, which of the following numbers might NOT be generated by Next(n)?

    <p>5</p> Signup and view all the answers

    In what scenario would Next(n) return a value of 4?

    <p>If n is 5</p> Signup and view all the answers

    What can be inferred about the method value regarding its dependency on class instances?

    <p>It is independent of the specific instance.</p> Signup and view all the answers

    Why are the method and the field declared as static?

    <p>To allow multiple instances to share the same data.</p> Signup and view all the answers

    Which characteristic best describes static methods in relation to instances?

    <p>They do not depend on the state of any instance.</p> Signup and view all the answers

    If a method is static, what implication does it have on the method's relationship with object instances?

    <p>It can be invoked without any instantiated object.</p> Signup and view all the answers

    In which scenario is it most appropriate to declare a method as static?

    <p>When the method's operations do not require access to instance data.</p> Signup and view all the answers

    What does the static property TickCount return?

    <p>The number of milliseconds passed since the computer was turned on</p> Signup and view all the answers

    What type of class is Sequence in the provided program?

    <p>The content does not specify the type of the class</p> Signup and view all the answers

    What does the static nature of the TickCount property imply?

    <p>It can be accessed without creating an instance of the class</p> Signup and view all the answers

    How is the value of TickCount measured?

    <p>In milliseconds from when the computer was turned on</p> Signup and view all the answers

    Which class contains the TickCount property?

    <p>Environment</p> Signup and view all the answers

    Study Notes

    Software Development - ITATCITO3 - Lecture 6

    • Objectives:
      • Familiarize with object-oriented programming (OOP) concepts: classes and objects.
      • Explain how to use .NET Framework classes from standard libraries.
      • Discuss commonly used system classes and their instantiation.
      • Demonstrate accessing object fields, calling constructors, and working with static fields.

    Classes and Objects

    • Object-oriented programming (OOP) is a programming paradigm using objects and their interactions to build computer programs.
    • This approach makes problem-solving intuitive.

    What is an Object?

    • Software objects model real-world objects (people, cars, etc.).
    • Objects have characteristics:
      • States (attributes): define the object. Examples for a dog: name, fur color, breed.
      • Behavior (methods): actions the object can perform. Examples for a dog: barking, sitting, walking.
    • Objects combine data and actions in one.

    Classes, Attributes, and Behavior

    • A class defines an object's characteristics (attributes) and behavior (actions).
    • Attributes are variables within the class.
    • Behavior is defined by methods within the class.
    • Example: a Dog class would have attributes like breed, furColor, and methods like bark(), sit(), and walk().

    Objects – Instances of Classes

    • An object is an instance of a class.
    • Creating an object is called instantiation.
    • Objects have a state (values) and behavior (methods) associated with the class.

    Classes in C#

    • C# classes are defined with the keyword class.
    • Classes contain:
      • Fields: member variables of a specific type.
      • Properties: special fields enhancing data management.
      • Methods: implement data manipulation.

    An Example Class (Cat)

    • The Cat class models a cat with the attributes Name and Color.

    Dealing with Class Cat

    • The Cat class keeps its values in private fields (name, color).
    • Two constructors are defined (with and without parameters).
    • Example of using the Cat class including Main method.

    System Classes

    • System.Console: a system class used in C# applications (e.g., Console.WriteLine).
    • String, Environment, Math: standard libraries for building applications.

    Creating and Using Objects – I

    • Creating objects from defined classes is performed via the new operator.
    • The object's reference, not a copy of the object, is stored in the variable.
    • Objects are created on the heap, while variables referring to them reside on the stack.

    Creating Objects with Set Parameters (more details)

    • Creating objects of a class with specific parameter values when instantiated.
    • These parameters initialize the object's attributes.
    • Objects are stored in memory, and references are used to access them.

    Access to Fields and Methods of an Object

    • Access object fields, methods, and properties using the dot operator (e.g., myCat.Name).

    Constructors – I

    • Constructors are special class methods automatically called when an object is created.
    • Constructors initialize the object's data.
    • They have the same name as the class.
    • Can be parameterless or parameterized.

    Constructors – II

    • The example provided shows parameterless and parameterized constructors, where constructors are initialized differently.

    Static Fields and Methods – I

    • Static members (fields and methods) are associated with the class, not specific objects.
    • Static members can be used without creating an object of that class.

    Static Fields and Methods – II

    • Static fields are initialized when the class is first used, not when objects are created.

    Static Fields and Methods – III

    • This section describes the NextValue() method which increments a value each time it's called, demonstrating a static method's behavior.

    Static Fields and Methods – IV

    • The Sequence class example demonstrates static members, where a private constructor prevents instantiation of the class.

    Examples of System C# Classes (Environment)

    • Environment.TickCount: returns the number of milliseconds since the computer started.

    System.Math Class

    • System.Math class provides mathematical functions (e.g., Math.PI, trigonometric functions).

    System.Random Class

    • System.Random class for generating random numbers.
    • Using Next(n) generates a random number in the range [0, n).

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    Description

    This quiz covers essential concepts in object-oriented programming (OOP), focusing on classes and objects. You will explore the use of .NET Framework classes, their instantiation, and the manipulation of object fields and methods. Test your understanding of OOP principles and their application in software development.

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