C++ Primer Plus

Unwinding the Stack

Suppose a try block doesn’t contain a direct call to a function that throws an exception but that it calls a function that calls a function that throws an exception. Execution still jumps from the function in which the exception is thrown to the function that contains the try block and handlers. Doing so involves unwinding the stack, which we’ll discuss now.

First, let’s look at how C++ normally handles function calls and returns. C++ typically handles function calls by placing information on a stack (see Chapter 9, “Memory Models and Namespaces”). In particular, a program places the address of a calling function instruction (a return address) on the stack. When the called function completes, the program uses that address ...