Nullable value types in C Sharp (C#) - Mini Project: Build & Apply

Nullable Value Types in C#

📖 Scenario: Imagine you are building a simple program to track the ages of people. Sometimes, the age might not be known yet, so you need a way to represent that missing information.

🎯 Goal: You will create a program that uses nullable value types to store ages, check if an age is known, and display the ages or a message if the age is unknown.

📋 What You'll Learn

Create a nullable integer variable to store an age.

Create a boolean variable to check if the age has a value.

Use an if statement to print the age if it exists or print 'Age is unknown' if it does not.

Use the int? type for nullable integers.

💡 Why This Matters

🌍 Real World

Nullable value types are useful when you need to represent missing or optional data, such as ages, dates, or measurements that might not be known yet.

💼 Career

Understanding nullable types is important for writing safe and clear code in C#, especially when working with databases, user input, or APIs where data might be incomplete.

1

Create a nullable integer variable

Create a nullable integer variable called age and set it to null.

C Sharp (C#)

# Your code here

Need a hint?

Use int? to make an integer nullable and assign null to it.

2

Create a boolean to check if age has a value

Create a boolean variable called hasAge and set it to age.HasValue.

C Sharp (C#)

int? age = null;
# Your code here

Need a hint?

Use the HasValue property to check if age has a value.

3

Use an if statement to check and print age

Write an if statement that checks hasAge. If true, print age.Value. Otherwise, print "Age is unknown".

C Sharp (C#)

int? age = null;
bool hasAge = age.HasValue;
# Your code here

Need a hint?

Use age.Value to get the actual age when it exists.

4

Change age and print again

Set age to 30 and update hasAge accordingly. Then print the age or the unknown message again using the same if statement.

C Sharp (C#)

int? age = null;
bool hasAge = age.HasValue;
if (hasAge)
{
    System.Console.WriteLine(age.Value);
}
else
{
    System.Console.WriteLine("Age is unknown");
}
# Your code here

Need a hint?

Remember to update hasAge after changing age.