Try-catch works with structured exception

[George2]

Hello everyone,


I have tested try-catch works with structured exception, to my surprise. Previously I think we have to use __try and __except.

Any comments? Here is my test code and I am using Visual Studio 2008.

#include <iostream>
 
using namespace std;
 
int main()
{
    int* address = NULL;
 
    try{
 
        (*address) = 1024;
    } catch (...)
    {
        cout << "access violation caught" << endl;
    }
    return 0;
}
 

thanks in advance,
George

[weaknessforcats]

Windows only supports structured exception handling (SEH). Your C++ try/catch/throw are really compiled as __try/__except/throw. The throw os a call to RaiseException(). In this case an access violation by attempting to reach outside your process address space.

Since this is a Win32 exception, you can catch these as an int so you can lookup the error.

However, if you actually write a __try/__except/throw youcan field the exception in the __except block and after admonishing whoever is responsible you could EXCEPTION__CONTINUE_EXECUTION and keep your program alive. Visual Studio does not make this flag available in a C++ catch block.

[George2]

Thanks weaknessforcats,


Interesting reply. Two more comments,

1.

Windows only supports structured exception handling (SEH). Your C++ try/catch/throw are really compiled as __try/__except/throw. The throw os a call to RaiseException(). In this case an access violation by attempting to reach outside your process address space.

How do you know try/catch is compiled as __try/__except? Any macro definitions make this true or?

2.

However, if you actually write a __try/__except/throw youcan field the exception in the __except block and after admonishing whoever is responsible you could EXCEPTION__CONTINUE_EXECUTION and keep your program alive. Visual Studio does not make this flag available in a C++ catch block.

Sorry, for my limited knowledge, I do not quite understand what do you mean "EXCEPTION__CONTINUE_EXECUTION and keep your program alive", at least I have never seen and used EXCEPTION__CONTINUE_EXECUTION in Visual Studio. Any more description or show some pseudo code please?


regards,
George

[weaknessforcats]

I just posted a URL on another thread that should cover this.

[George2]

Thanks weaknessforcats,


I will read it further. :-)

I just posted a URL on another thread that should cover this.

regards,
George