Object type as universal base in C Sharp (C#) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a variable that can hold any type of value.

C Sharp (C#)

object [1] = 42;

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Aobj

Bany

Cdata

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Using a reserved keyword as variable name

Using a type name instead of a variable name

In C#, object is the universal base type. You can name the variable anything, but obj is a common choice.

2fill in blank

medium

Complete the code to assign a string value to an object variable.

C Sharp (C#)

object obj = [1];

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Anull

B100

C"hello"

Dtrue

Attempts:

3 left

💡 Hint

Common Mistakes

Using single quotes instead of double quotes for strings

Assigning a number instead of a string

Strings in C# are enclosed in double quotes. Assigning a string literal to an object variable is allowed.

3fill in blank

hard

Fix the error in the code by completing the cast from object to string.

C Sharp (C#)

object obj = "test";
string s = ([1])obj;

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Astring

Bint

Cbool

Ddouble

Attempts:

3 left

💡 Hint

Common Mistakes

Casting to a wrong type causes runtime errors

Forgetting to cast causes compile errors

To convert an object holding a string back to a string, you must cast it to string.

4fill in blank

hard

Fill both blanks to create an object array and assign different types of values.

C Sharp (C#)

object[] arr = new object[] { [1], [2] };

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

A"hello"

B42

Ctrue

D3.14

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around numbers

Mixing up boolean and numeric values

An object array can hold any types. Here, a string and an integer are assigned.

5fill in blank

hard

Fill all three blanks to create a method that returns an object and assigns different types inside.

C Sharp (C#)

public object GetValue(int choice) {
    return choice switch {
        1 => [1],
        2 => [2],
        _ => [3]
    };
}

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

A"apple"

B100

Cfalse

Dnull

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around booleans or numbers

Returning incompatible types without casting

The method returns different types as objects based on the input choice: a string, an integer, or a boolean.