HP aC++/HP C A.06.20 Programmer's Guide

These classes provide a common framework for the way errors are handled in a C++
program. System-specific error handling can be provided by creating classes that inherit
from these standard exception classes.
Example
# include <stdexcept>
# include <iostream>
# include <string>
void f()
{
// details omitted
throw range_error(string(“some info”));
}
void main()
{
try {
f();
}
catch (runtime_error& r) {
// handle any kind of runtime error including range_error
cout << r.what() << ‘\n’;
}
}
The class logic_error defines objects thrown as exceptions to report errors due to
the internal logic of the program. The errors are presumably preventable and detectable
before execution. Examples are violations of logical preconditions or class invariants.
The subclasses of logic_error are:
• domain_error (the operation requested is inconsistent with the state of the object
it is applied to)
• invalid_argument
• length_error (an attempt to create an object whose size equals or exceeds
allowed size)
• out_of_range (an argument value not in the expected range)
Runtime errors are due to events out of the scope of the program. They cannot be
predicted before they happen. The subclasses of runtime_error are:
• range_error
• overflow_error (arithmetic overflow)
The exception class includes a void constructor, a copy constructor, an assignment
operator, a virtual destructor, and a function what that returns an
implementation-defined character string. None of these functions throw any exceptions.
Each of the subclasses includes a constructor taking an instance of the Standard C++
Library string class as an argument. They initialize an instance such that the function
Standard Exception Classes 195