Unit 2: C# Programming Fundamentals - Practice Quiz

1 Which C# data type is commonly used to store a whole number?

2 Which statement displays Hello World in a C# console application?

3 What is the value of 2 + 3 * 4 in C#?

4 Which C# statement executes code only when a specified condition is true?

5 Which loop always executes its body at least once?

6 Which jump statement immediately exits the nearest loop?

7 Which declaration creates a one-dimensional integer array with five elements?

8 Which expression returns the number of elements in an array named scores?

9 Which string method converts "hello" to "HELLO"?

10 Which operator can join two strings in C#?

11 Which object-oriented concept allows one method name to have different behaviors?

12 What is an object in C#?

13 Which access modifier restricts a class member so it can be accessed only within the same class?

14 When is a constructor normally called in C#?

15 Which symbol is used to specify a base class in a C# class declaration?

16 Which keyword allows a base-class method to be replaced with a derived-class implementation?

17 Which statement about an abstract class in C# is correct?

18 Which block contains code that might cause an exception?

19 What does the continue statement do inside a loop?

20 Which block is used to handle an exception thrown by code in a try block?

21 What happens when the following C# code is compiled?

var quantity = 10;
quantity = 10.5;

22 What is the output of the following program?

class Program
{
static void Main()
{
Console.Write("Hello");
Console.WriteLine(" World");
Console.Write("C#");
}
}

23 What value is printed by the following code?

int a = 5, b = 2;
int result = a++ * --b + a;
Console.WriteLine(result);

24 What is printed by this nested conditional statement?

int x = 12;
if (x % 2 == 0)
if (x > 10)
Console.Write("A");
else
Console.Write("B");
else
Console.Write("C");

25 What value is printed after this loop finishes?

int sum = 0;
for (int i = 1; i <= 5; i++)
{
if (i % 2 == 0) continue;
sum += i;
}
Console.WriteLine(sum);

26 What does the following loop print?

for (int i = 0; i < 7; i++)
{
if (i == 2) continue;
if (i == 5) break;
Console.Write(i);
}

27 What is printed by the following jagged-array code?

int[][] values =
{
new int[] { 1, 2 },
new int[] { 3, 4, 5 }
};
Console.WriteLine(values[1][2]);

28 What value is printed after the array is sorted and reversed?

int[] numbers = { 7, 2, 9, 4 };
Array.Sort(numbers);
Array.Reverse(numbers);
Console.WriteLine(numbers[1]);

29 What is the output of the following string operation?

string text = "Modern Web";
Console.WriteLine(text.Substring(7, 3).ToUpper());

30 What is printed by this code?

string language = "C#";
language.Replace("#", "Sharp");
Console.WriteLine(language);

31 An application defines an INotification interface with a Send() method. EmailNotification and SmsNotification provide different implementations of Send(). Which OOP concept is primarily demonstrated when both objects are used through INotification references?

32 Given the class Student with a public integer field Mark, what is printed?

Student first = new Student();
first.Mark = 70;
Student second = first;
second.Mark = 85;
Console.WriteLine(first.Mark);

33 Which design best encapsulates a bank account balance while preventing negative deposits?

34 What is printed when the following object is created?

class Base
{
public Base() { Console.Write("Base "); }
}
class Derived : Base
{
public Derived() { Console.Write("Derived"); }
}

Derived item = new Derived();

35 A base class declares protected int code = 10;. Which statement about code is correct?

36 What is printed by the following code?

class Animal
{
public virtual void Speak() { Console.Write("Animal"); }
}
class Dog : Animal
{
public override void Speak() { Console.Write("Dog"); }
}

Animal pet = new Dog();
pet.Speak();

37 Consider the following declaration:

abstract class Shape
{
public abstract double Area();
}

What must a non-abstract class derived from Shape do?

38 What is printed by the following code?

try
{
int value = int.Parse("abc");
Console.Write("Parsed ");
}
catch (FormatException)
{
Console.Write("Invalid ");
}
finally
{
Console.Write("Done");
}

39 What value is printed by the following expression?

int result = 8 >> 1 + 1;
Console.WriteLine(result);

40 What does the following program print?

static int GetValue()
{
int value = 1;
try
{
return value;
}
finally
{
value = 2;
}
}

Console.WriteLine(GetValue());

41 What does the following C# code print?

byte value = 250;
var result = value + 10;
Console.Write($"{result}:{result.GetType().Name}");

42 A top-level C# program contains the following code and is run without command-line arguments. What are its console output and process exit code?

Console.Write($"{args.Length}:{Environment.ExitCode}");
return 7;

43 What value is assigned to result?

int result = 1 + 2 * 3 << 1 & 15;

44 What does this code print?

int x = 0;

if (++x == 1 || ++x == 2 && ++x == 3)
{
    x += 10;
}

Console.Write(x);

45 What does the following loop print?

int i = 0;
int sum = 0;

do
{
    i++;
    if (i % 2 == 0)
        continue;

    sum += i;
}
while (i < 4);

Console.Write(sum);

46 What is printed when F() is called?

static int F()
{
    try
    {
        goto Done;
    }
    finally
    {
        Console.Write("F");
    }

Done:
    Console.Write("D");
    return 1;
}

Console.Write(F());

47 What happens when this code is executed?

object[] values = new string[2];
values[0] = "valid";
values[1] = 42;
Console.Write(string.Join(",", values));

48 What does this code print?

int[,] rectangular = new int[2, 3];
int[][] jagged =
{
    new int[1],
    new int[4]
};

Console.Write($"{rectangular.Length},{rectangular.GetLength(1)},{jagged.Length},{jagged[1].Length}");

49 What is the final content of numbers?

int[] numbers = { 1, 2, 3, 4, 5 };
Array.Copy(numbers, 0, numbers, 1, 4);

50 What does this code print on a modern .NET runtime?

string input = "  a ,, b,  ";
string[] parts = input.Split(
    ',',
    StringSplitOptions.TrimEntries |
    StringSplitOptions.RemoveEmptyEntries);

Console.Write($"{parts.Length}:{string.Join("|", parts)}");

51 What does the following code print?

string first = "ab" + "cd";
string second = new string(new[] { 'a', 'b', 'c', 'd' });

Console.Write($"{first == second}:{ReferenceEquals(first, second)}");

52 What does this code print?

interface ILeft
{
    string Name();
}

interface IRight
{
    string Name();
}

class Both : ILeft, IRight
{
    string ILeft.Name() => "L";
    string IRight.Name() => "R";
    public string Name() => "P";
}

var item = new Both();
ILeft left = item;
Console.Write(item.Name() + left.Name() + ((IRight)item).Name());

53 What does this code print?

class Box
{
    public int Value;
}

static void Update(Box box)
{
    box.Value = 2;
    box = new Box { Value = 3 };
}

var original = new Box { Value = 1 };
Update(original);
Console.Write(original.Value);

54 Which property declaration allows assignment only from the containing class or from derived classes located in the same assembly, while allowing public reads?

55 What is the output when new Derived() is executed?

class Base
{
    protected static int Mark(string text)
    {
        Console.Write(text);
        return 0;
    }

    private int b = Mark("Bf ");

    public Base()
    {
        Console.Write("Bc ");
    }
}

class Derived : Base
{
    private int d = Mark("Df ");

    public Derived()
    {
        Console.Write("Dc");
    }
}

56 What does this code print?

class Base
{
    public string Show() => "Base";
}

class Derived : Base
{
    public new string Show() => "Derived";
}

Base item = new Derived();
Console.Write(item.Show());

57 What does this code print?

class Base
{
    public virtual string M(object value) => "Base-object";
}

class Derived : Base
{
    public override string M(object value) => "Derived-object";
    public string M(string value) => "Derived-string";
}

Base item = new Derived();
Console.Write(item.M("text"));

58 What does this code print?

class A
{
    public virtual string Describe() => "A";
}

abstract class B : A
{
    public abstract override string Describe();
}

class C : B
{
    public override string Describe() => "C";
}

A value = new C();
Console.Write(value.Describe());

59 What does the following code print?

static bool Filter()
{
    Console.Write("L");
    return false;
}

try
{
    try
    {
        throw new InvalidOperationException();
    }
    catch (Exception) when (Filter())
    {
        Console.Write("C");
    }
    finally
    {
        Console.Write("F");
    }
}
catch (Exception)
{
    Console.Write("O");
}

60 What does this code print?

static int Calculate()
{
    int value = 1;

    try
    {
        return value;
    }
    finally
    {
        value = 2;
        Console.Write(value);
    }
}

Console.Write(Calculate());