How Do Exceptions Work in C : An Exception Stack

How do exceptions really work?

Exceptions in C work by creating a separate stack, known as the "exception stack," that stores information about the exception that was thrown. When an exception is thrown, the program jumps to the nearest matching catch block, and the exception object is passed to the catch block. The catch block can then handle the exception appropriately, such as by logging the error or taking other recovery actions.

The process of handling an exception involves several steps:

1. Exception is thrown: When an exception is thrown, the current execution state is saved on the exception stack. This includes the program counter, the stack pointer, and the registers.
2. Exception propagation: The exception propagates up the call stack, looking for a matching catch block. If no matching catch block is found, the program terminates.
3. Exception handling: When a matching catch block is found, the program jumps to the catch block and the exception object is passed to the catch block.
4. Exception recovery: The catch block handles the exception and performs any necessary recovery actions, such as logging the error or taking other recovery actions.
5. Exception unwinding: After the exception has been handled, the program unwinds the exception stack, restoring the program counter, stack pointer, and registers to the state they were in before the exception was thrown.

The use of an exception stack allows the program to continue execution even after an error has occurred. This allows the program to handle errors gracefully and perform any necessary cleanup before terminating.

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