Welcome to the GDNet C# Workshop – Ch. 1 & 2

Chapters 1 & 2 – Introduction & Lexical Structure

1. Hello World
2. Program Structure
3. Types and Variables
4. Expressions
5. Statements
6. Classes and Objects
7. Structs
8. Arrays
9. Interfaces
10. Enums
11. Delegates
12. Attributes

1. Programs
2. Grammars
3. Lexical Analysis
4. Tokens
5. Pre-Processing Directives

Good Luck!

1. What is component-oriented programming?

Contemporary software design increasingly relies on software components in the form of self-contained and self-describing packages of functionality


2. What are the keys to software components in C#?

Key to such components is that they present a programming model with properties, methods, and events; they have attributes that provide declarative information about the component; and they incorporate their own documentation


3. What is Garbage Collection?

Garbage collection automatically reclaims memory occupied by unused objects;


4. What is exception Handling?

exception handling provides a structured and extensible approach to error detection and recovery;


5. What benefits do type safety provide you in C#?

design of the language makes it impossible to have uninitialized variables, to index arrays beyond their bounds, or to perform unchecked type casts.


6. What is a unified type system?

All C# types, including primitive types such as int and double, inherit from a single root object type.


7. What are the benefits of a unified type system?

all types share a set of common operations, and values of any type can be stored, transported, and operated upon in a consistent manner.


8. What's the purpose of namespaces?

Namespaces provide a hierarchical means of organizing C# programs and libraries.


9. What directive allows unqualified use of the members of a namespace?

The 'using' directive.


10. What is the entry point of a C# Console application?

A static method named "main."


11. What's the name of the C# Runtime libraries?

The .NET Framework Library


12. What are the key organizational concepts in C#?

Programs, namespaces, types, members, and assemblies.


13. What two things do C# assemblies contain and what form are they in?

Executable code in the form of Intermediate Language and symbolic information in the form of metadata


14. What happens to the IL instructions just before the code is executed?

It is converted into processor-specific code by the JIT compiler of the .NET CLR.


15. When are forward decelerations needed in C#?

Never.


16. What are the two kinds of variable types in C# what's the difference?

Valye types and reference types. Value types store data directly, reference types store references to their data.


17. How are C#'s value types subdivided?

simple types, enum types, and struct types.


18. How are C#'s reference types subdivided?

Class types, interface types, array types, and delegate types.


19. What is the encoding of a C# character, and how much memory does a single character require?

Unicode encoding. It requires 16-bits.

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20. What are the sizes of each of the Simple Types, and their range of values?



21. Which 5 categories of C# types are user-definable types?

class, struct, interface, enum, and delegate.


22. Give an overview of each of the 5 types.

A class type defines a data structure that contains data members (fields) and function members (methods, properties, and others). Class types support inheritance and polymorphism, mechanisms whereby derived classes can extend and specialize base classes.

A struct type is similar to a class type in that it represents a structure with data members and function members. However, unlike classes, structs are value types and do not require heap allocation. Struct types do not support user-specified inheritance, and all struct types implicitly inherit from type object.

An interface type defines a contract as a named set of function members. A class or struct that implements an interface must provide implementations of the interface’s function members. An interface may inherit from multiple base interfaces, and a class or struct may implement multiple interfaces.

An enum type is a distinct type with named constants. Every enum type has an underlying type, which must be one of the eight integral types. The set of values of an enum type is the same as the set of values of the underlying type.

A delegate type represents references to methods with a particular parameter list and return type. Delegates make it possible to treat methods as entities that can be assigned to variables and passed as parameters. Delegates are similar to the concept of function pointers found in some other languages, but unlike function pointers, delegates are object-oriented and type-safe.

23. What is "boxing" and "unboxing"

The process of casting a C# value type to an object.


24. What are expressions?

Expressions are constructed from operands and operators


25. What is the relationship between operators and operands in an expression?

Operators tell what operation to perform on the operands.


26. What is an operator's precedence?

A rule which governs the order in which the operator is evaluated relative to other operators.


27. What is operator overloading?

Operator overloading permits user-defined operator implementations to be specified for operations where one or both of the operands are of a user-defined class or struct type.


28. What are the different kinds of C# statements, and what do they do??

Blocks - Allows multiple other statements in place of a single statements
Decelerations - declare variables and constants
Expressions - Evaluate an expression.
Selection - Also called branching, changes the flow of execution
Iteration - Similar to branching, allows execution of the same code repeatedly with some variance
Jump - Similar to branching, changes the scope of execution
Try...catch - Used to catch exceptions
Checked/unchecked - Used for checking underflow and overflow in integral types
Lock - Use for mutually exclusive locks of data for thread safety
using - use to temporarily obtain resources and dispose of them.


29. What is a class?

A class is a data structure that combines state (fields) and actions (methods and other function members) in a single unit.


30. Create an example class named Character. Dont worry about members, methods, or properties

public class Character
{

}


31. What operator is used to create a new instance of a class? What's the syntax to create a Character object?

The new operator
Character myCharacter = new Character();


32. What are the different types of members of a class?


Constants - The constant values associated with the class
Fields - The variables of the class
Methods - The computations and actions that can be performed by the class
Properties - The actions associated with reading and writing named properties of the class
Indexers - The actions associated with indexing instances of the class like an array
Events - The notifications that can be generated by the class
Operators - The conversions and expression operators supported by the class
Constructors - The actions required to initialize instances of the class or the class itself
Destructors - The actions to perform before instances of the class are permanently discarded
Types - The nested types declared by the class


33. What are the 5 types of Accessibility used on a class's members?


public - Access not limited
protected - Access limited to this class and classes derived from this class
internal - Access limited to this program
protected internal -Access limited to this program and classes derived from this class
private Access limited to this class


34. What does inheritance mean?

Inheritance means that a class implicitly contains all members of its base class, except for the constructors of the base class


35. What is a field?

A field is a variable that is associated with a class or with an instance of a class.


36. What is the difference between a static and non-static field?

A static field has exactly one memory storage location, which is shared by all instances of a class. non-static is a unique
memory address for each instance.


37. What is a method of a class?

A method is a member that implements a computation or action that can be performed by an object or class.


38. What's the difference between static and non-static methods?

Static methods are accessible from the class, while non-static are accessible from the instances of the class, or "objects."


39. What are parameters?

list of arguments, which represent values or variable references passed to the method


40. What are return types?

specifies the type of the value computed and returned by the method


41. What does a signature of a method consist of?

The signature of a method consists of the name of the method and the number, modifiers, and types of its parameters. The signature of a method does NOT include the return type.


42. What are the 4 types of parameters and how are they used?

Value, reference, output, and arrays. Value is for input parameters. Reference parameters are used for both input and output. Output parameters are used simply for outgoing parameter passing. Parameter arrays allow a variable number of arguments to be passed into the method.


43. What is a static method?

A method declared with a static modifier. It does not operaote on a specific instance of a class, and can only access static members.


44. What is an instance method?

Any method created without the static modifier. It operates on specific instance of the class, and can access both static and non-static members.


45. What's the difference between a virtual and non-virtual method?

When a virtual method is invoked, it's runtime type for the instance is invoked. For a non-virtual method, the compile-time type is invoked.


46. What does it mean to override a virtual method?

The method overrides an inherited virtual method with the same signature, thus providing a new implementation for that method.


47. What is an abstract method and when is it permitted?

A method with no implementation. It is only permitted in classes also declared abstract.


48. What is method overloading?

Method overloading permits multiple methods in the same class to have the same name, so long as they have unique signatures.


49. What is the difference between an instance constructor and a static constructor?

Instance constructors are called when an object is created, to initialize the object. Static constructors are called by the CLR when a class is loaded, and is used to initialize the class itself.


50. What is the primary difference between properties and fields?

Properties do not denote storage locations, and instead provide accessors which specify the statements to be executed when their values are read or written to.


51. How do you make a property read-only?

Dont provide a set method.


52. What is an indexer?

An indexer is a member that enables object to be indexed in the same way as an array. It is declared like a property, except the name is always "this" followed by a parameter list written between square brackets.


53. What is an event, and what is true of it's type?

An event is a member that enables a class or object to provide notifications. The type must always be a delegate.


54. What are event handlers?

Event handlers are methods attached to an event using the += operator and removed with the -= operator.


55. What is a class operator?

Its a member that defines (re-defines) the meaning of applying a particular expression operator to instances of the class.


56. What is a destructor?

A member that implements the actions required to destruct an instance of a class - specifically non-garbage collected member data.


57. What's the main difference between classes and structs?

Structs are value types instead of the reference types, and can be created on the stack, rather than the heap. A struct directly stores the data of the struct, while a class stores a reference to an object. Also, structs do not support inheritance.


58. What is an array?

An array is a data structure that contains a number of variables of the same type that are accessed through computed indices.


59. What is an array initializer?

A way of initializing the values within an array during construction of the array.


60. What is an interface, and what can it contain?

An interface defines a contract that can be implemented by classes and structs. An interface can contain methods, properties, events, and indexers.


61. What are enums?

enums are a value type which contain a set of named, symbolic constants.


62. What is an enum's underlying type?

All enums have an underlying integral type. Those that are not specified have default underlying type of 'int'.


63. What is a delegate?

A delegate represents references to methods with a particular parameter list and return type. Delegates make it possible to treat methods as variables which can be assigned and passed as parameters.


64. What is the purpose of attributes?

To allow user-defined types of declarative information that can be attached to program entities and retrieved at run-time.


65. What is a compilation unit in C#?

It's a source file


66. What are the 3 steps in compiling a program?

1. Transformation
2. Lexical Analysis
3. Syntatic Analysis


67. What encoding are C# files in? ie. ASCII?

Unicode


68. What is the purpose of lexical grammar?

It defines how Unicode characters are combined to form line terminators, white space, comments, tokens, and pre-processing directives.


69. What is the purpose of syntactic grammar?

Defines how the tokens resulting from the lexical grammar are combined to form C# programs.


70. What is contained within the first line of a grammar rule?

The non-terminal symbol being defined, followed by a colon.


71. When you see the suffix "opt" in a grammar rule, what does it mean?

It means the previous term is optional.


72. What are the five basic elements that make up the structure of a C# source file?

Line terminators, white space, comments, tokens, and pre-processing directives.


73. Which of the 5 elements of a C# source file are relevant to the syntax of a C# file?

The tokens.


74. What do line terminators do?

divide the characters of C# source files into lines.


75. What are the two forms of comments supported by C#, give examples.

Single line comments, which start with // and comment out everything else on the line...and...
Delimited comments, which are anything between /* and */, even spanning multiple lines.


76. What are the 5 types of tokens?

Identifiers, Keywords, literals, operators, and punctuators.


77. List ALL of the C# keywords



abstract	as		base		bool		breakbyte		case		catch		char		checkedclass		const		continue	decimal		defaultdelegate	do		double		else		enumevent		explicit	extern		false		finallyfixed		float		for		foreach		gotoif		implicit	in		int		interfaceinternal	is		lock		long		namespacenew		null		object		operator	outoverride	params		private		protected	publicreadonly	ref		return		sbyte		sealedshort		sizeof		stackalloc	static		stringstruct		switch		this		throw		truetry		typeof		uint		ulong		uncheckedunsafe		ushort		using		virtual		voidvolatile	while



78. What is a literal, and what are the 6 types of literals?

A source code representation of an actual value.
boolean
integer
real
character
string
null


79. Give an example of each type of literal.

true
200
200.23
'c'
"Hello, World"
null


80. What is a verbatim literal string, and how is it created?

A verbatim literal is one with a @ at the beginning, and in a verbatim string, escape characters are not interpreted.


81. What are the possible Pre-processing directive, what is their function, and what is their intended use?

#define, #undef - defining and undefing symbols
#if, #elif, #else, #endif controling conditional compilation based on the existance of defined symbols
#line changing the line number and file name of source.
#error and #warning, used to generate compile-time warnings and errors
#region and #endregion used to group lines of source code for a programmer.

using System;class Hello{    static void Main()     {	Console.WriteLine("My name is Jeromy Walsh");    }}

Quote: Original post by Alpha_ProgDes
First question. What's the difference between readonly and const? They seem to do the same thing.

Quote: Second question. A delegate is a first class property. And a function pointer (in C++) isn't? But can't you declare and pass function pointers around just like you can delegates? I guess I'm asking what's the real difference.

Quote: Original post by hpjchobbes
What is the main difference between REF and OUT? It seems like they could be interchanged and the code would still operate the same.

int x;x += 2; // error, as x is not guaranteed to have been initialized to 0

Quote:
A reference parameter is used for both input and output parameter passing

Quote:
An output parameter is used for output parameter passing.

// Please do not write code like this// It's only an examplevoid SquareOut(int x, out int y){    y = x * x;}void SquareRef(int x, ref int y){    y = x * x;}void Func1(){    int result; // uninitialized    SquareOut(2, out result); // will work}void Func2(){    int result; // uninitialized    SquareRef(2, ref result); // won't work}

void SomeFuncWithOut(out int x){    Console.WriteLine( x ); // error    x = 1;    Console.WriteLine( x ); // ok}

1. A local variable is initially uninitialized.


2. Reading an uninitialized variable is an error.


3. Assignment initializes a variable.


4. An incoming ref variable is assumed to be initialized.


5. An incoming out variable is assumed to be uninitialized.


6. It is forbidden to pass an uninialized variable using ref.