Error handling and exception safety in C++

13 Sep 2023

Error handling and exception safety are crucial aspects of writing robust and reliable code in C++. In this blog post, we will explore these concepts and discuss best practices to ensure a robust error-handling mechanism and maintain exception safety in your C++ programs.

Error Handling

C++ provides several mechanisms for error handling, including return codes, exceptions, and assertions. Each method has its own advantages and considerations, so it’s essential to choose the appropriate approach based on the situation.

Return Codes: Return codes are a common way to indicate errors in C++. Functions can return special values or predefined error codes to signal failure. However, this approach can sometimes lead to code clutter and make error handling code more complex.
Exceptions: C++ exceptions provide a more robust error handling mechanism. When an exceptional condition occurs, such as an invalid input or a runtime error, an exception can be thrown and caught by appropriate exception handling blocks. Exceptions allow for cleaner code and separate error handling logic from regular code execution.
```
try {
    // code that may throw an exception
} catch (const std::exception& e) {
    // handle exception
}
```
Assertions: Assertions are mainly used during development and debugging to catch logical errors or enforce program invariants. They help identify and fix bugs early in the development process. Assertions typically result in program termination if the specified condition fails.
```
assert(condition);
```

Exception Safety

Exception safety focuses on ensuring that objects, data structures, and resources remain in a consistent state, even in the presence of exceptions. It involves handling exceptions in a way that prevents resource leaks, maintains invariants, and provides strong or basic exception guarantees.

No-Throw Guarantee: Some operations should never throw exceptions, ensuring a no-throw guarantee. This can be achieved by using appropriate techniques like exception specifications, noexcept operators, or using libraries that provide a no-throw guarantee.
Strong Exception Guarantee: The strong exception guarantee ensures that if an exception occurs, the program state remains unchanged, and no resources are leaked. It involves creating a copy of the object before performing any operations, and only modifying the original object if the operation succeeds.
Basic Exception Guarantee: The basic exception guarantee ensures that if an exception occurs, all resources are released and no leaks occur. However, the program state may be different from the original state, and some invariants may have been violated. Proper cleanup and resource release are crucial to achieving basic exception safety.

Conclusion

Effective error handling and maintaining exception safety are vital for writing robust and reliable C++ code. By choosing the appropriate error handling mechanism and following exception safety guidelines, you can improve the quality and resilience of your code. Remember to handle exceptions carefully, release resources properly, and strive for strong or basic exception guarantees whenever possible.

#Cplusplus #ExceptionSafety