Multiple Choice Questions (with solutions)

Why are the instructors sharing most of the material in odt, docx, pdf, html and md?

• To insure compatibility across operating systems (Android, Linux, Windows, MacOs, …).
• To make it easier to access the resources in multiple ways (print, screen, etc.)
• All of the above.

What does “free” software means?

• That the software has no value.
• That the users can run the software for any purpose and study its source code.
• That it is not developed by a company.
• That the software can be downloaded at no cost.

In your IDE, the shortcut to compile your program is usually…

• “Build your solution”, ctrl + shift + B or Cmd + B
• “Save”, ctrl + S or Cmd + S
• “Exit”, alt + F4 or Cmd + q
• “Start without debugging”, Ctrl + F5 or Cmd + F5

To share or backup a project, you need to…

• share the .sln file.
• share the .cs file.
• share the .csproj file.
• zip the folder containing the .sln file and another folder with multiple files and folders in it.

If your IDE returns the message

Program.cs(21,21): Error CS0117: 'Console' does not contain a definition for 'WiteLine' (CS0117) (Solution)

This means that…

• That you misspelled the word “WriteLine”.
• Your program successfully compiled and is ready to be executed.
• That the “Console” class does not exist.
• Your IDE was not properly installed and you should reboot your computer.

Consider the following code:

int age, defaultChoice = 0;
decimal averagePrice;

Which of the following is correct?

• It contains declaration and initialization statements.
• It declares variables of two different datatypes.
• Only the value of defaultChoice is set.
• All of the above.

Consider the following code:

int person = 12;
int pie = 5;
int piePerPerson = pie / person;
Console.WriteLine("Each guest gets " + piePerPerson + " pie(s).");

What will be displayed by it?

• Nothing: an error will prevent from compiling it successfully.
• “Each guest gets 2.4 pie(s).”
• “Each guest gets 0.41666666666666666666666…” (it will never ends, displaying 6 forever).
• “Each guest gets 0.416666666666667 pie(s).”
• “Each guest gets 0 pie(s).”

Consider the following statement:

decimal balance = 2.5M;
decimal price = 12;
decimal remainingBalance = balance - price;

Which of the following is correct?

• This program will not compile because the result of balance - price is not a decimal.
• This program will not compile because a decimal cannot be negative.
• This program will compile.
• This program will not compile because you cannot store an integer value (12) in a decimal.

The method used to read a string from the user is called…

• ReadString
• ReadFrom
• ReadLine
• ReadInput

Consider the following program:

Console.WriteLine("Enter your age.");
string fromUser = Console.ReadLine();
int age = _______ (fromUser);

To correctly be able to store the string in fromUser into age, you should replace _______ with…

• (int)
• int.Parse
• Nothing: as long as the user enters an integer value, we can store it into age just fine.
• None of the above.

What are, respectively, the return types of a constructor and of a ToString method?

• Constructors do not have a return type, and a ToString method returns a string.
• Constructors and ToString methods both return strings.
• Constructors returns a string, and a ToString method does not return anything (it simply displays a text).
• It is impossible to know ahead of time, as this depends of the class they are implemented in.

What is the name of a constructor method?

• Nothing: an error will prevent from compiling it successfully.
• Whatever the name of the class is.
• It does not have any.
• The name of the instance it creates.
• Constructor

What are the three logical connectives in C# (that we studied)?

• And (&&), or (||) and negation (!).
• Equality (==), greater than (>) and less than (<).
• And (and), or (or) and negation (not).

Which of the following will evaluate to true?

• 3 > 1 && 2
• (3 > 1) && 1 != 0
• !(3 > 1)
• 3 > 1 || 2

Will the following expression evaluates, and if so, what will it evaluate to?

true == false || 2 / 1 > 0 && 3 - 1 != 2 * 0.5 + 0.5

evaluates?

• It will evaluate to a number.
• It will evaluate to false.
• It will evaluate to true.
• It will not evaluate.
• None of the above.

What will be displayed by the following code?

int number = 10;
while (number <= 15)
{
    number+=2;
    Console.Write(number + " ");
}

• 12 14 16
• 10 11 12 13 14 15
• 10 11 12 13 14
• 10 12 16
• 10 12
• 10 12 14
• 12+14+16
• 10+11+12+13+14+15

What will be displayed by the following code?

int i = 0;
while(i < 10)
{
    Console.WriteLine(i);
}

• 0 followed by a new line, forever.
• 0 1 2 3 4 5 6 7 8 9
• 0 1 2 3 4 5 6 7 8 9 with a new line between each number
• Nothing

Consider the following code:

Console.WriteLine("Enter… something!");
int answer;
bool valid = int.TryParse(Console.ReadLine(), out answer);
Console.WriteLine($"returns: {valid}, value:{answer}");

If the user enters “Train”, then it will display:

• returns: False, value: 0
• returns: True, value: 0
• returns: True, value: Train
• returns: False, value: Train
• Nothing: the program will crash.

Consider the following code:

string answer;
Console.WriteLine("Enter something");
answer = Console.ReadLine();
while (answer != "yes" || answer !="Yes"){
    Console.WriteLine("Enter something");
    answer = Console.ReadLine();
}

What can the user enters to exit this loop:

• There is nothing the user can enter to exit this loop
• Either “Yes” or “yes”
• Anything that is different from “Yes” and “yes”
• Anything

Consider the following code:

int answer;
Console.WriteLine("Enter something");
answer = int.Parse(Console.ReadLine());
while (answer > 10 && answer < 100){
    Console.WriteLine("Enter something");
    answer = int.Parse(Console.ReadLine());
}

What can the user enters to exit this loop?

• Any number not between 10 and 100 (both included)
• Any number between 10 and 100 (both included)
• Any number between 10 and 100 (both excluded)
• Any number not between 10 and 100 (both excluded)

What is the correct way of creating an array of int of size 5 named myArray?

• int[] myArray = new int[5];
• int[] myArray = int[5];
• int[5] myArray = new int[];
• int[4] myArray = new int[];
• int myArray = new int[5];
• int[] myArray = new int[4];
• int[] myArray = new int(5);
• int[] myArray = int[4];

Consider the following code:

int[] grades = {10, 20, 5, 15};
Console.WriteLine(grades[2]);

What will it display?

• 5
• Nothing
• 20
• 15
• grades
• grades[2]
• 10

Consider the following code:

char[] grades = {'A', 'B', 'C', 'D', 'F'};
int i = 0;
while(i < grades.Length){
    i++;
    Console.WriteLine(grades[i]);
}

Something is wrong with it, can you tell what?

• There will be an “Index was outside the bounds of the array.” error.
• The array is not properly initialized.
• The loop is infinite
• grades.Length is not declared.

What will be displayed by the following code?

for (int e = -5; e <= 20; e += 5)
{
    Console.Write(e + " ");
}

• -5 0 5 10 15 20
• -5 0 5 10 15
• 0 5 10 15
• -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
• Nothing
• 0 5 10 15 20

What will be displayed by the following code?

int variable = 0;
for (int e = 1; e <= 5; e += 1)
{
    variable += e;
}    
Console.WriteLine(variable);

• 15
• 0
• Nothing
• 1 2 3 4 5