Catch by Value or Reference in C Exception Handling: Which is Better?

Exception Handling in C : Catch by Value or Reference

When handling exceptions in C , it is essential to consider whether to catch by value or reference. This decision can have significant implications on code behavior.

Preferred Approach: Throw by Value, Catch by Reference

The standard practice for exception handling in C is to throw exceptions by value and catch them by reference. This approach addresses potential issues with inheritance hierarchies.

Example:

class CustomException {
public:
    int errorCode;
};

class MyException : public CustomException {
public:
    // Overridden error code
    int errorCode = 404;
};

Catching by Value:

If an exception is caught by value, it is directly converted to the type specified in the catch block. This conversion can lead to unintended behavior, as demonstrated with the following code:

try {
    // Throw a MyException object
    throw MyException();
} catch (CustomException e) { // Catch by value
    // e is converted to a CustomException object
    // Error code is now 200 instead of 404
    ...
}

Catching by Reference:

In contrast, catching by reference ensures that the original exception object is handled. This preserves the actual error code and allows for proper handling of inherited exceptions.

try {
    // Throw a MyException object
    throw MyException();
} catch (CustomException& e) { // Catch by reference
    // e references the original MyException object
    // Error code remains 404
    ...
}

Conclusion:

Although it is possible to catch exceptions by value in C , the recommended practice is to throw by value and catch by reference. This approach prevents potential issues caused by inheritance and ensures accurate handling of exceptions.

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