What is the purpose of IDisposable?

Q: What is the purpose of IDisposable?

IDisposable provides a mechanism for releasing unmanaged resources deterministically.

Q: When should a class implement IDisposable?

When it uses unmanaged resources that require explicit cleanup.

💡 Concept: IDisposable Interface

IDisposable is an interface in C# used to release unmanaged resources like file handles, database connections, or unmanaged memory.

📘 Quick Intro

Implementing IDisposable ensures deterministic cleanup of resources that the garbage collector doesn’t handle.

🧠 Analogy

Think of IDisposable as a contract that promises to clean up after yourself, like returning library books after reading.

🔧 Technical Explanation

🧹 IDisposable defines a Dispose() method for resource cleanup.
⚙️ Used to free unmanaged resources deterministically.
🔄 Often used with the using statement for automatic disposal.
🛠️ Helps prevent resource leaks and improves application stability.
🔐 Classes managing unmanaged resources should implement IDisposable.

🎯 Use Cases

✅ Closing database connections.
✅ Releasing file handles.
✅ Cleaning up unmanaged memory.
✅ Ensuring timely disposal of resources.

💻 Code Example


public class ResourceHolder : IDisposable {
    private bool disposed = false;

    public void Dispose() {
        Dispose(true);
        GC.SuppressFinalize(this);
    }

    protected virtual void Dispose(bool disposing) {
        if (!disposed) {
            if (disposing) {
                // Free managed resources here.
            }
            // Free unmanaged resources here.
            disposed = true;
        }
    }

    ~ResourceHolder() {
        Dispose(false);
    }
}

❓ Interview Q&A

Q1: What is IDisposable used for?
A: To release unmanaged resources.

Q2: How does Dispose() work?
A: It frees resources deterministically.

Q3: What is the using statement?
A: A syntax sugar for IDisposable to auto-dispose.

Q4: When should a class implement IDisposable?
A: When it uses unmanaged resources.

Q5: What does GC.SuppressFinalize do?
A: Prevents finalizer from running if already disposed.

Q6: Can Dispose be called multiple times?
A: Should be safe and idempotent.

Q7: What is finalizer (~ClassName)?
A: Backup cleanup if Dispose not called.

Q8: Why use IDisposable with unmanaged resources?
A: GC doesn’t handle unmanaged resources.

Q9: What happens if Dispose not called?
A: Resource leaks and issues.

Q10: How to implement Dispose pattern?
A: Use Dispose(bool) with suppression.

📝 MCQs

Q1. What is IDisposable?

Class
Interface for cleanup
Method
Exception

Q2. What does Dispose() do?

Creates objects
Frees resources
Handles errors
Manages threads

Q3. What is the using statement?

Loop
Auto-dispose syntax
Exception handler
Class definition

Q4. When to implement IDisposable?

Always
Never
When using unmanaged resources
Only in console apps

Q5. What does GC.SuppressFinalize do?

Runs finalizer
Prevents finalizer
Creates GC
Disposes object

Q6. Can Dispose be called multiple times?

No
Should be safe
Sometimes
Never

Q7. What is a finalizer?

Constructor
Backup cleanup
Method
Property

Q8. Why use IDisposable?

Ignore resources
Handle unmanaged resources
Optimize CPU
Log errors

Q9. What if Dispose not called?

No effect
Resource leaks
App crash
GC fixes

Q10. How to implement Dispose pattern?

Use Dispose(bool)
Ignore
Use finalizer only
Throw exceptions

💡 Bonus Insight

Proper implementation of IDisposable is crucial for robust and resource-efficient C# applications.

📄 PDF Download

Need a handy summary for your notes? Download this topic as a PDF!

📄 PDF Download Coming Soon