Object type as universal base in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this code using object as base?

Consider this C# code where object is used as a universal base type. What will be printed?

C Sharp (C#)

object val = 123;
Console.WriteLine(val.GetType());

A System.Int32

B System.Object

C 123

D System.String

💡 Hint

Remember that object can hold any type, but GetType() returns the actual runtime type.

The variable val holds an integer value 123. Although declared as object, the actual type is System.Int32. So GetType() returns System.Int32.

❓ Predict Output

intermediate

What is the output when casting object to string?

What will this code print?

C Sharp (C#)

object val = "hello";
string s = (string)val;
Console.WriteLine(s.Length);

A System.String

B 5

C hello

D Runtime error

💡 Hint

Check the length of the string stored inside the object.

The object val holds a string "hello". Casting it back to string works fine. The length of "hello" is 5.

🔧 Debug

advanced

Why does this code cause an exception?

Examine the code below. Why does it throw an exception at runtime?

C Sharp (C#)

object val = 42;
string s = (string)val;
Console.WriteLine(s);

A Compile-time error due to invalid cast

B NullReferenceException because val is null

C InvalidCastException because int cannot be cast to string

D No exception, prints 42

💡 Hint

Think about what types can be cast directly to string.

The variable val holds an int boxed as object. Casting directly to string causes InvalidCastException because int and string are unrelated types.

🧠 Conceptual

advanced

What is the result of using object.Equals with different types?

What does this code print?

C Sharp (C#)

object a = 10;
object b = "10";
Console.WriteLine(a.Equals(b));

A False

B Runtime exception

C Compile-time error

D True

💡 Hint

Check if Equals compares values or types.

The Equals method returns false because a is an int and b is a string, so they are not equal.

❓ Predict Output

expert

What is the output of this polymorphic object array?

Given this array of objects holding different types, what will be printed?

C Sharp (C#)

object[] arr = { 1, "two", 3.0 };
foreach (var item in arr)
{
    Console.WriteLine(item.GetType().Name);
}

A

1
two
3.0

B

Object
Object
Object

C

int
string
double

D

Int32
String
Double

💡 Hint

Remember GetType() returns the runtime type of each element.

The array holds an int, a string, and a double boxed as objects. GetType().Name returns their actual type names: Int32, String, Double.