C# Academy · Lesson

HasValue and Value Properties

Inspect and access nullable values safely.

HasValue and Value Properties is a free C# Academy lesson on CoddyKit — lesson 2 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the C# Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

Two Key Properties

Every nullable exposes HasValue (a bool) and Value (the underlying value). They are your tools for inspecting it safely.

using System;

class Program {
    static void Main() {
        int? n = 5;
        Console.WriteLine(n.HasValue);
        Console.WriteLine(n.Value);
    }
}

HasValue Checks Presence

HasValue is true when a real value is present and false when it is null.

using System;

class Program {
    static void Main() {
        int? a = 10;
        int? b = null;
        Console.WriteLine(a.HasValue);
        Console.WriteLine(b.HasValue);
    }
}

Reading Value Safely

Always check HasValue before reading Value, because reading Value on a null throws.

using System;

class Program {
    static void Main() {
        int? n = 42;
        if (n.HasValue) {
            Console.WriteLine(n.Value * 2);
        }
    }
}

Accessing Value on Null Throws

If you read Value when the nullable is null, C# throws an InvalidOperationException. The check protects you.

using System;

class Program {
    static void Main() {
        int? n = null;
        try {
            Console.WriteLine(n.Value);
        } catch (InvalidOperationException) {
            Console.WriteLine("Caught: no value");
        }
    }
}

GetValueOrDefault

GetValueOrDefault() returns the value if present, otherwise the type default (0 for int, false for bool).

using System;

class Program {
    static void Main() {
        int? n = null;
        Console.WriteLine(n.GetValueOrDefault());
    }
}

GetValueOrDefault with Fallback

Pass an argument to choose your own fallback: GetValueOrDefault(99) returns 99 when null.

using System;

class Program {
    static void Main() {
        int? n = null;
        Console.WriteLine(n.GetValueOrDefault(99));
        int? m = 7;
        Console.WriteLine(m.GetValueOrDefault(99));
    }
}

Pattern: Check Then Use

A common pattern combines HasValue and Value into a clean branch.

using System;

class Program {
    static void Describe(int? score) {
        if (score.HasValue)
            Console.WriteLine("Score is " + score.Value);
        else
            Console.WriteLine("No score yet");
    }
    static void Main() {
        Describe(88);
        Describe(null);
    }
}

Implicit Conversion Back

You can assign a nullable to a plain type only after confirming it has a value, then read Value.

using System;

class Program {
    static void Main() {
        int? maybe = 15;
        if (maybe.HasValue) {
            int real = maybe.Value;
            Console.WriteLine(real + 5);
        }
    }
}

Default of Nullable

A nullable not explicitly set defaults to null, so HasValue is false.

using System;

class Program {
    static void Main() {
        int? n = default;
        Console.WriteLine(n.HasValue);
    }
}

Using in Aggregations

Loop over data, skipping nulls with HasValue, to compute safe totals.

using System;

class Program {
    static void Main() {
        int?[] readings = { 10, null, 5, null, 8 };
        int sum = 0;
        foreach (var r in readings)
            if (r.HasValue) sum += r.Value;
        Console.WriteLine(sum);
    }
}

GetValueOrDefault in Loops

GetValueOrDefault can simplify code where null should be treated as zero.

using System;

class Program {
    static void Main() {
        int?[] readings = { 10, null, 5 };
        int sum = 0;
        foreach (var r in readings)
            sum += r.GetValueOrDefault();
        Console.WriteLine(sum);
    }
}

Quick Check

Test your knowledge of nullable properties.

Recap

HasValue tells you whether a nullable holds a value, and Value retrieves it, but reading Value on a null throws.

GetValueOrDefault() safely returns the value or a fallback (the type default or one you supply), making it ideal for sums and safe reads.

Frequently asked questions

Is the “HasValue and Value Properties” lesson free?

Yes — the full text of “HasValue and Value Properties” is free to read here on the web, and the C# Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the C# Academy course, upgrade to CoddyKit PRO.

What will I learn in “HasValue and Value Properties”?

Inspect and access nullable values safely. You practise C# Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start C# Academy?

No prior experience is required. C# Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 2 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “HasValue and Value Properties” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this C# Academy lesson?

Yes. Every C# Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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