Performance implications of boxing in C Sharp (C#) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to box the integer value into an object.

C Sharp (C#)

int number = 42;
object boxedNumber = [1];

Drag options to blanks, or click blank then click option'

A(object)number

Bnumber.ToString()

Cnumber

Dref number

Attempts:

3 left

💡 Hint

Common Mistakes

Using the variable directly without casting does not box it explicitly.

Using ToString() converts to string, not boxing.

Using ref keyword is for references, not boxing.

Boxing an integer means converting it to an object type. Using (object)number explicitly boxes the value.

2fill in blank

medium

Complete the code to unbox the object back to an integer.

C Sharp (C#)

object boxedNumber = 100;
int originalNumber = ([1])boxedNumber;

Drag options to blanks, or click blank then click option'

Astring

Bint

Cobject

Ddouble

Attempts:

3 left

💡 Hint

Common Mistakes

Casting to a different type causes runtime errors.

Casting to object does not unbox.

Casting to string or double is incorrect here.

Unboxing requires casting the object back to the original value type, which is int here.

3fill in blank

hard

Fix the error in the code that tries to unbox an object to a double.

C Sharp (C#)

object boxedValue = 10;
double value = ([1])boxedValue;

Drag options to blanks, or click blank then click option'

Aobject

Bstring

Cdouble

Dint

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to unbox directly to a different value type causes exceptions.

Casting to string or object does not unbox.

The object actually holds an int, so unboxing must use int first, then convert to double if needed.

4fill in blank

hard

Fill both blanks to create a dictionary that maps integers to their boxed objects only if the integer is greater than 5.

C Sharp (C#)

var numbers = new List<int> {3, 7, 10};
var dict = numbers.Where(n => n [2] 5).ToDictionary(n => n, n => [1]);

Drag options to blanks, or click blank then click option'

A(object)n

Bn >

C>

Dn <

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect comparison operators.

Not boxing the integer properly.

Placing the condition incorrectly.

We box each integer with (object)n and filter with n > 5 to include only numbers greater than 5.

5fill in blank

hard

Fill all three blanks to create a method that accepts an object, checks if it is a boxed int, and returns its value multiplied by 2.

C Sharp (C#)

public int DoubleIfBoxedInt(object obj) {
    if (obj is [1] value) {
        return value [2] 2;
    }
    return [3];
}

Drag options to blanks, or click blank then click option'

Aint

B*

C0

Ddouble

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong type in pattern matching.

Using incorrect operator for multiplication.

Returning wrong default value.

The is int value pattern unboxes the object if it holds an int. Then multiply by 2 with *. Return 0 if not an int.