16.2.2 Exceptions

Exception handling is a language feature present in other modern programming languages. Ada and Java both have exception handling mechanisms. In essence, exception handling is a means of propagating a classified error by unwinding the procedure call stack until the error is caught by a higher procedure in the procedure call chain. A procedure indicates its willingness to handle a kind of error by catching it:

void foo (); void func () { try { foo (); } catch (...) { cerr << "foo failed!" << endl; } }

Conversely, a procedure can throw an exception when something goes wrong:

typedef int io_error; void init () { int fd; fd = open ("/etc/passwd", O_RDONLY); if (fd < 0) { throw io_error(errno); } }

C++ compilers tend to implement exception handling in full, or not at all. If any C++ compiler you may be concerned with does not implement exception handling, you may wish to take the lowest common denominator approach and eliminate such code from your project.