Exercising C++ exception handling.

Notes

The essentials of exception handling in c++:

when compiling c++, exception handling is usually turned on by default. But this can be compiler-specific and require switches to enable
mulitple catch blocks allow catching different types of errors
noexcept specifier indicates the method cannot throw an exception. Bad practice generally.
- noexcept is an improved version of throw(), which is deprecated in C++11
polymorphism applies: must catch exception subclasses before ancestors

Demo

exception_handling.cpp runs through a variety of exception classes that are caught:

simple ints
simple char messages
string messages
custom exception classes
polymorphic standard exceptions

..and ends on an uncaught exception.

NB: this is updated for C++17 syntax - specifically the use of noexcept instead of throw().

$ g++ -std=c++17 -o exception_handling.exe exception_handling.cpp && ./exception_handling.exe

Testing a range of standard and custom exceptions..

Error code: 33
Basic error message: Oh deary me
String error message caught by reference: Out of bacon
bad_alloc error message caught by reference: std::bad_alloc
Generic exception error message caught by reference: std::exception
CustomException message caught by reference: Something bad happened

Now testing an exception in a constructor..

exception_handling.exe(28207,0x7fffae28f380) malloc: *** mach_vm_map(size=1000000000000000) failed (error code=3)
*** error: can't allocate region
*** set a breakpoint in malloc_error_break to debug
bad_alloc message: std::bad_alloc

And we're still running!

But the next has no handler:

libc++abi.dylib: terminating with uncaught exception of type int
Abort trap: 6

Notes

Demo

Credits and References