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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 ();

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

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

typedef int io_error;

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.

This document was generated by Gary V. Vaughan on February, 8 2006 using texi2html