Mixing C (structured) and C++ exceptions

If you want to write portable code, the use of structured exception handling (SEH) in a C++ program isn't recommended. However, you may sometimes want to compile using /EHa and mix structured exceptions and C++ source code, and need some facility for handling both kinds of exceptions. Because a structured exception handler has no concept of objects or typed exceptions, it can't handle exceptions thrown by C++ code. However, C++ catch handlers can handle structured exceptions. C++ exception handling syntax (try, throw, catch) isn't accepted by the C compiler, but structured exception handling syntax (__try, __except, __finally) is supported by the C++ compiler.

See _set_se_translator for information on how to handle structured exceptions as C++ exceptions.

If you mix structured and C++ exceptions, be aware of these potential issues:

• C++ exceptions and structured exceptions can't be mixed within the same function.

• Termination handlers (__finally blocks) are always executed, even during unwinding after an exception is thrown.

• C++ exception handling can catch and preserve the unwind semantics in all modules compiled with the /EH compiler options, which enable unwind semantics.

• There may be some situations in which destructor functions aren't called for all objects. For example, a structured exception could occur while attempting to make a function call through an uninitialized function pointer. If the function parameters are objects constructed before the call, the destructors of those objects don't get called during stack unwind.

Next steps

• Using setjmp or longjmp in C++ programs

  See more information on the use of setjmp and longjmp in C++ programs.

• Handle structured exceptions in C++

  See examples of the ways you can use C++ to handle structured exceptions.

See also

Modern C++ best practices for exceptions and error handling