Terminology

Question 1

what is a class?

Answer 1

A class is like a blueprint of a specific object. A class enables you to create your custom types by grouping variables of other types, methods, and events.

Question 2

What is the difference between a class and an object?

Answer 2

In c#, Classes and Objects are interrelated. The class in c# is nothing but a collection of various data members (fields, properties, etc.) and member functions. The object in c# is an instance of a class to access the defined properties and methods.

Question 3

What are namespaces in c# .NET?

Answer 3

Namespaces are used in C# to organize and provide a level of separation of codes. They can be considered as a container which consists of other namespaces, classes, etc.

Question 4

what is a boolean and what is it’s default value?

Answer 4

Boolean value= True or False default: False

Question 5

what is a byte and what is it’s range and default value?

Answer 5

8-bit unsigned integer from 0 to 255 default=0

Question 6

name 3 variable types that require a letter also-

Answer 6

decimal =m double = d float = f

Question 7

what is type conversion and what are it’s 2 forms?

Answer 7

Type conversion is converting one type of data to another type. It is also known as Type Casting. In C#, type casting has two forms − Implicit type conversion − These conversions are performed by C# in a type-safe manner. For example, are conversions from smaller to larger integral types and conversions from derived classes to base classes. Explicit type conversion − These conversions are done explicitly by users using the pre-defined functions. Explicit conversions require a cast operator. example: ———————————————- Using System; namespace TypeConversionApplication { class StringConversion { static void Main(string[] args) { int i = 75; float f = 53.005f; double d = 2345.7652; bool b = true; Console.WriteLine(i.ToString()); Console.WriteLine(f.ToString()); Console.WriteLine(d.ToString()); Console.WriteLine(b.ToString()); Console.ReadKey(); } } }

Question 8

what is a variable?

Answer 8

A variable is nothing but a name given to a storage area that our programs can manipulate. Each variable in C# has a specific type, which determines the size and layout of the variable’s memory the range of values that can be stored within that memory and the set of operations that can be applied to the variable.

Question 9

What is an interface?

Answer 9

basically like a contract-it tells a class what must be in it.

Question 10

what are the 4 things an interface can define?

Answer 10

1. methods 2. properties 3. indexes 4.events

Question 11

what forces a class to implement any of 4 pieces of information?

Answer 11

interfaces

Question 12

are interfaces public or private?

Answer 12

interfaces are ALWAYS public

Question 13

what is the naming convention for Interfaces

Answer 13

always start with capital “I” then the name such as “IMyInterface”

Question 14

what is the default access modifier for Interfaces?

Answer 14

public- Interfaces must be public therefore if no access modifier is given the default is public

Question 15

if you define a method within an Interface- what should the access modifier be?

Answer 15

you can drop the access modifier because Interfaces are always public

Question 16

how do you define a method within Interfaces?

Answer 16

with only the method signature: void LogMessage(string message); normal declaration: public void LogMessage(string message) { Console.WriteLine(“your message”); }

Question 17

what is dependency injection and what is it’s intent?

Answer 17

Dependency Injection (DI) is a software design pattern. It allows us to develop loosely-coupled code. The intent of Dependency Injection is to make code maintainable. Dependency Injection helps to reduce the tight coupling among software components. Dependency Injection reduces the hard-coded dependencies among your classes by injecting those dependencies at run time instead of design time technically.

Question 18

what is a constructor?

Answer 18

A constructor is a special method of the class which gets automatically invoked whenever an instance of the class is created. Like methods, a constructor also contains the collection of instructions that are executed at the time of Object creation.

Question 19

name 7 important things to remember about constructors-

Answer 19

1. Constructor of a class must have the same name as the class name in which it resides.
2. A constructor can not be abstract, final, static and Synchronized.
3. Within a class, you can create only one static constructor.
4. A constructor doesn’t have any return type, not even void.
5. A static constructor cannot be a parameterized constructor.
6. A class can have any number of constructors.
7. Access modifiers can be used in constructor declaration to control its access i.e which other class can call the constructor.

Question 20

what is a constructor?

Answer 20

a method that is called with an instance of a class is created

Question 21

why do we need a constructor?

Answer 21

the intention is to put an object in a early state

-that is to initialize some of the fields in the class

Question 22

what is constructor overloading?

Answer 22

having a method by the same name but different signatures

Question 23

what is a method signature?

Answer 23

a dignature is what uniquely identifies a method

that is:

its name

its return type

and the types and number of its perameters

Question 24

What is an object initializer?

Answer 24

a syntax for quickly initializing an object without the need to call one of its constructors

Question 25

why do we need object initializers?

Answer 25

to avoid creating multiple constructors

Question 26

what is the syntax for an object initializer?

Answer 26

see image

Question 27

what does it mean to overload a method?

Answer 27

having a method with the same name but different signatures

-see image

Question 28

how does one use the Params modifier and why?

Answer 28

when there are too many possible constructors the code -see image

one could use an array but then the array must be initialized before each use

instead use a Params Modifier

Question 29

What is an access modifier?

Answer 29

An access modifier is a way to control access to a control and/or its members (such as public or private)

Question 30

what is a property?

Answer 30

a property is a class member that encapsulates a getter/setter for accessing a field

A property is a member that provides a flexible mechanism to read, write, or compute the value of a private field. Properties can be used as if they are public data members, but they are actually special methods called accessors.

Question 31

what is an Indexer?

Answer 31

Indexer is a special kind of property that allows accessing elements of a list by an index. - If a class has the semantics of a list, or collection, we can define an indexer property for it. This way it’s easier to get or set items in the collection.

-see image (cookie [“name”]= “mosh”;

is indexer

Question 32

What is class coupling?

Answer 32

Class coupling is a measure of the dependencies a class has on other classes. This dependency is measured through parameters, method calls and interface implementations, just to name a few. The higher this number, the more likely a change in one class will affect other classes.

Question 33

what’s the problems with Inheritance?

Answer 33

see attached

Question 34

Name the 5 access modifiers

Answer 34

see attached