What should I know about Structured Exceptions (SEH) in C++?

c++ exception exception-handling seh structured-exception
Andrew T picture Andrew T · May 6, 2010 · Viewed 34.6k times · Source

What important points about Structured Exceptions should every C++ developer know?

Answer

Ben Voigt picture Ben Voigt · May 6, 2010

They are the Win32 equivalent to Unix signals, and let you catch CPU exceptions such as access violation, illegal instruction, divide by zero.

With the right compiler options (/EHa for Visual C++), C++ exceptions use the same mechanism as stack unwinding works properly for both C++ (user) exceptions and SEH (OS) exceptions.

Unlike C++ exceptions, SEH are not typed but all share the same data structure which has an exception code (the cause) and additional information on what code faulted and what the CPU registers held at the time of the fault. See GetExceptionCode and GetExceptionInformation for more details on this.

Also, SEH has "first-chance" handling, which allows you to log or otherwise handle the exception before unwinding destroys all the local variables.

Related questions

C++ display stack trace on exception

I want to have a way to report the stack trace to the user if an exception is thrown. What is the best way to do this? Does it take huge amounts of extra code? To answer questions: I'd like …

Read More
How to throw std::exceptions with variable messages?

This is an example of what I often do when I want to add some information to an exception: std::stringstream errMsg; errMsg << "Could not load config file '" << configfile << "'"; throw std::exception(…

Read More
Should I inherit from std::exception?

I've seen at least one reliable source (a C++ class I took) recommend that application-specific exception classes in C++ should inherit from std::exception. I'm not clear on the benefits of this approach. In C# the reasons for inheriting from …

Read More