Unit 1 - CH 2

Question 1

Define Variable

Answer 1

A location in memory that contains one or more data values

Question 2

Define Identifier

Answer 2

A unique name given to a variable, procedure, or function, etc

Question 3

Define High-level programming language

Answer 3

A language that has English-like keywords and commands to express the basic constructs of sequence, selection, and iteration

Question 4

Define Integer Division

Answer 4

A process that returns only the whole number section of a division.

E.g. 7/2 = 3.5 but integer division would return 3

Question 5

Define Compiler

Answer 5

A program that translates source code into executable object code

Question 6

Define Console Application

Answer 6

A program that runs on a text-based window into which the user types and which displays text output from the computer

Question 7

C# Integer Division

Answer 7

int wholeNumberPart = num1 / num2

Question 8

C# modulo operation

Answer 8

int remainder = num1 % num2

Question 9

C# commenting

Answer 9

Single line 
// comment

Multi line
/* comments */

Question 10

C# user input

Answer 10

string input = Console.Readline ()

Question 11

C# display/output

Answer 11

Display and leave cursor on same line
Console.Write (“Heya”)

Display and move cursor to newline
Console.WriteLine (“Coolio”)

Question 12

C# string formatting layout

Answer 12

Console.WriteLine(“{0} plus {1} is {2}”, num1, num2, sum);

Question 13

Define Global variable

Answer 13

A variable declared at the beginning of a program and accessible from anywhere in the program.

Not always desirable as its values 0may be accidentally changed

Question 14

Define Local variable

Answer 14

A variable declared in a program block and only accessible within the scope of that routine.

Question 15

Define Constant

Answer 15

A variable whose value does not change throughout the program runtime

Question 16

What is the difference between an integer and a real number?

Answer 16

Integers are whole numbers, real numbers can have a fractional part/decimal point.

Question 17

Why use int instead of real?

Answer 17

They use less memory and store values accurately.

Question 18

Define string

Answer 18

A sequence of zero or more characters

Question 19

Define character

Answer 19

Any letter, number, or symbol in a character set such as ASCII

Question 20

C# string accessing

Answer 20

charThree = aString [4]

Zero-indexed

Question 21

C# dateTime usage

Answer 21

dateTime today;
today = DateTime.Today;

dateTime tomorrow = today.AddDays (1);

dateTime anniversary = System.Convert.ToDateTime (“08/09/2017”);

Question 22

Define Record

Answer 22

A data structure that groups a number of variables.

Lightweight classes, basically.

Question 23

What data structure is this?

struct Book
   {
      public string Title, ISBN;
      public decimal Price;
      public int PublicationYear;
   }

Book theMazeRunner;
theMazeRunner.Title = “The Maze Runner”

Answer 23

Defining and then initializing a record in C#

Question 24

Define Enumerated type

Answer 24

An ordered set of values

Question 25

Define Field

Answer 25

A variable that is part of a record

Question 26

Define Set

Answer 26

A collection of values of the same ordinal type with no associated order.

Question 27

What are the 4 set operators?

Answer 27

1. Union (set3 = set1 + set2): values from both sets minus duplicates 2. Difference (set3 = set1 - set2): all set1 values that are not in set2 3. Intersection (set3 = set1 * set2): only values found in both sets 4. Membership (if a in set1 then): tests whether a value is in a set

Question 28

What are the 4 logical bitwise operators?

Answer 28

NOT AND OR XOR

Question 29

What are the 3 Boolean operators?

Answer 29

AND NOT OR

Question 30

What are the relational operators?

Answer 30

``` == < > != <= >= ```

Question 31

C# nested IF statement

Answer 31

if (condition){ } else if (alternate condition){ } else{ }

Question 32

C# switch case statement

Answer 32

``` switch (x){ case 4: z += 1; break; case 5: z -= 1; Console.Write (x); break; } ```

Question 33

Difference between nested IF statements and switch case statements?

Answer 33

IF statements are executed when a condition is met (e.g. x > 5) Case statements are executed when a variable x has a specific value (e.g. case 6)

Question 34

C# for loop

Answer 34

for (int count=1; count <5; count++) { Console.WriteLine (count) } Used when the number of iterations is known and finite

Question 35

C# foreach loop

Answer 35

foreach (name in namesList) { Console.WriteLine(name); } Good for inspecting every element in an array

Question 36

C# do while loop

Answer 36

``` do { Console.Write ("Your name: "); name = Console.ReadLine (); } while (name != "Ash"); ```

Question 37

What is the difference between passing parameters by reference and passing by value?

Answer 37

Calling by reference: Passes a reference to the memory location of the variable to another procedure. Anything done to the variable in this procedure will also change it's value elsewhere. Calling by value: A copy of the variable is passed to the called procedure and anything done to it has no effect outside the procedure scope.

Question 38

C# one dimensional array

Answer 38

string[ ] arrayName = {"I'm", "an", "array"}; arrayName [0] = "I am"; Console.Write(arrayName [0], arrayName [2]); OUTPUT:: I am array

Question 39

C# two dimensional array

Answer 39

int [ , ] arrayName = new int [4,4] arrayName [0,3] = 123 #Accesses first row, fourth column

Question 40

In C#, array elements have to be of the same datatype. Parallel arrays of different datatypes are inefficient; how do you go around this?

Answer 40

Create an array of records (custom datatype struct) recordDataType [ ] arrayName = new recordDataType[5] arrayName [0].recordField1 = value

Question 41

What's a CSV file?

Answer 41

Comma Separated Values file. Text file with one record per line, and record fields separated by commas. Used as data files for mail-merge programs.

Question 42

What's a Binary file?

Answer 42

A file of records, usually containing multiple datatypes. Datatypes other than strings and chars are stored in internal format and can't be displayed in a meaningful way in a text editor (which only interprets ASCII or Unicode character codes).

Question 43

What's a Text file?

Answer 43

A sequence of printable characters organised line by line, which can be accessed and read in a text editor.

Question 44

C# Writing to a text file

Answer 44

``` static StreamWriter currentFileWriter; static void Main(string [ ] args) { string fileName = "filename.txt"; currentFileWriter = new StreamWriter(fileName); currentFileWriter.WriteLine("Hello World"); currentFileWriter.Close () } ```

Question 45

C# readimg a text file

Answer 45

``` static StreamReader currentFileReader; static void Main(string [ ] args) { string fileName = "filename.txt"; currentFileReader = new StreamReader(fileName); Console.WriteLine (currentFileReader.ReadLine()); currentFileReader.Close () } ```