Throwing your own exception in C++, and catching it

In C++ you can throw anything - it doesn't have to be something "throw-able" as in Java.

1. Create a class of objects that you want to throw in exceptional circumstances
2. When you want to throw an exception, use the throw keyword and pass in the object
3. Call the code that you want to catch the exception in a try block and
4. Add catch blocks after the try block to handle the exceptions.

Full example, with comments, [here].

There's a program using string objects - here - that shows how some of the C++ system classes throw exceptions ...

92:antrim graham$ ./prob

Please enter your details I am Graham Ellis and I am in Belfast at present

terminate called after throwing an instance of 'std::out_of_range'

  what():  basic_string::erase

Abort trap

92:antrim graham$

And here is a similar program but with an added exception handler:

92:antrim graham$ ./except

Please enter your details This is a further demonstration for you

Caught exception basic_string::erase

We could go on if we wanted

Although in this demo we'll exit nice

92:antrim graham$

See [here] for the failing code and [here] for the fixed code.
(written 2010-11-24, updated 2010-12-04)

Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles

C236 - C and C based languages - Exceptions
  [3509] Operator Overloading, Exceptions, Pointers, References and Templates in C++ - new examples from our courses - (2011-11-06)
  [2622] Handling unusual and error conditions - exceptions - (2010-02-03)
  [1875] What are exceptions - Python based answer - (2008-11-08)
  [799] The case for exceptions - (2006-07-11)

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