Advanced Error Handling Techniques in C++ Builder

Error handling in C++ Builder demands more than catching exceptions and logging generic messages. Sophisticated applications require precise strategies to manage errors gracefully, improve reliability, and maintain a seamless user experience. Yes, you can build robust, fault-tolerant software by applying practical, advanced techniques that catch problems early, handle them smartly, and keep users informed without breaking flow.

Why Basic Exception Handling Falls Short

Basic try-catch blocks might catch exceptions, but they often fail to distinguish between recoverable issues, critical faults, and user errors. Advanced techniques enable finer control, help anticipate failures, and allow systems to respond appropriately without unnecessary program crashes.

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1. Use Custom Exception Classes

Standard exceptions like std::exception and EException work for generic errors. Custom exception classes allow specific error information to be carried through the system.

class EDatabaseError : public Exception
{
public:
    __fastcall EDatabaseError(const String& Msg) : Exception(Msg) {}
};

Benefits of Custom Exceptions:

• Identify error types more accurately
• Attach additional data such as error codes or retry hints
• Allow fine-tuned catch blocks

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2. Implement Exception Safety Guarantees

C++ Builder applications often manipulate resources like memory, file handles, or database connections. Implementing exception safety ensures that no resource leaks occur during failures.

Levels of Exception Safety:

• Basic Guarantee: Resources remain valid and no leaks happen
• Strong Guarantee: Operation has no effect if it fails
• No-Throw Guarantee: Operation cannot fail

Techniques:

• Use RAII (Resource Acquisition Is Initialization) patterns
• Favor smart pointers like std::unique_ptr and std::shared_ptr
• Apply transactional techniques for batch operations

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3. Centralized Error Handling with Global Handlers

Instead of sprinkling error handling logic everywhere, configure global error handlers to catch unhandled exceptions.

void __fastcall TForm1::ApplicationEventsException(TObject *Sender, Exception *E)
{
    LogError(E->Message);
    ShowMessage("An unexpected error occurred. Please restart the application.");
}

Key Advantages:

• Ensures no exceptions slip through unnoticed
• Simplifies maintenance
• Provides a consistent error-reporting user interface

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4. Leverage Structured Exception Handling (SEH)

On Windows, C++ Builder can handle low-level OS exceptions like access violations using SEH.

__try
{
    int* p = nullptr;
    *p = 10;
}
__except(EXCEPTION_EXECUTE_HANDLER)
{
    ShowMessage("Access violation detected.");
}

Use Cases for SEH:

• Handling hardware exceptions
• Intercepting critical failures without crashing immediately
• Logging low-level faults for diagnostics

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5. Error Propagation and Wrapping

Instead of catching and logging immediately, propagate exceptions upward and wrap them with contextual information. This makes logs meaningful and assists debugging.

Example:

try
{
    LoadConfiguration();
}
catch(const Exception& E)
{
    throw Exception("Failed to load configuration: " + E.Message);
}

Why It Matters:

• Stack traces become easier to interpret
• End users get actionable messages
• Developers understand root causes faster

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6. Retry Logic for Transient Errors

Not all errors require user interruption. Transient errors like network timeouts can often be resolved by retrying automatically.

Example Retry Loop:

for (int i = 0; i < 3; ++i)
{
    try
    {
        ConnectToServer();
        break;
    }
    catch (const ESocketError&)
    {
        Sleep(1000); // Wait before retrying
    }
}

Where to Use:

• Database reconnections
• Network service calls
• File system access on busy servers

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7. Logging with Contextual Data

Logging raw exception messages does not help much in production. Enrich logs with:

• Function name
• User ID
• Timestamp
• Application state snapshot

Example Log Message:

[2025-04-04 10:15:23] Function: SaveOrder UserID: 1023 Error: Database timeout

Meaningful logs reduce diagnosis time dramatically and expose patterns across failures.

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Final Thoughts

Advanced error handling in C++ Builder transforms unstable code into resilient applications. Using custom exceptions, safety guarantees, global handlers, and smart retry strategies allows programs to continue operating reliably under pressure. Instead of merely reacting to errors, your application anticipates, manages, and recovers from them in a structured, user-friendly way.