How to Choose the Best Exception Handling Technique in C : By Value, Reference, or Pointer?

Exception Handling Techniques in C : Catching by Pointer

In C , exceptions can be caught in three distinct ways: by value, reference, or pointer. Each method has its own advantages and drawbacks.

Catch by Value

Copy semantics are employed when catching an exception by value. A new copy of the exception object is created, which involves duplicating the object's data. This can be inefficient for large objects.

Catch by Reference

When catching an exception by reference, the original exception object is referenced. No copying occurs, resulting in improved efficiency compared to catching by value. However, care must be taken to avoid dangling references.

Catch by Pointer

Catching an exception by pointer is similar to catching by reference, except that a pointer to the exception object is caught instead of a direct reference. This method provides the most control over exception handling, as it allows you to free the memory allocated for the exception object when it is no longer needed.

It's important to note that throwing a pointer to an exception object is generally discouraged. Instead, consider using a smart pointer (e.g., shared_ptr) to manage the memory of the exception object.

Recommendation

The standard C recommendation is to throw by value and catch by reference. This method is efficient and protects against dangling references.

Additional Note

In your example code:

class A {}

void f() {
  A *p = new A();
  throw p;
}

Throwing a pointer to an object is not recommended because it requires manual memory management at the catch site. If you need to throw an object, consider using a smart pointer, such as shared_ptr.

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