Simple:
#include
int compare( int a, int b ) {
if ( a < 0 || b < 0 ) {
throw std::invalid_argument( "received negative value" );
}
}
The Standard Library comes with a nice collection of built-in exception objects you can throw. Keep in mind that you should always throw by value and catch by reference:
try {
compare( -1, 3 );
}
catch( const std::invalid_argument& e ) {
// do stuff with exception...
}
You can have multiple catch() statements after each try, so you can handle different exception types separately if you want.
You can also re-throw exceptions:
catch( const std::invalid_argument& e ) {
// do something
// let someone higher up the call stack handle it if they want
throw;
}
And to catch exceptions regardless of type:
catch( ... ) { };
Though this question is rather old and has already been answered, I just want to add a note on how to do proper exception handling in C++11:
Use std::nested_exception and std::throw_with_nested
It is described on StackOverflow here and here, how you can get a backtrace on your exceptions inside your code without need for a debugger or cumbersome logging, by simply writing a proper exception handler which will rethrow nested exceptions.
Since you can do this with any derived exception class, you can add a lot of information to such a backtrace!
You may also take a look at my MWE on GitHub, where a backtrace would look something like this:
Library API: Exception caught in function 'api_function'
Backtrace:
~/Git/mwe-cpp-exception/src/detail/Library.cpp:17 : library_function failed
~/Git/mwe-cpp-exception/src/detail/Library.cpp:13 : could not open file "nonexistent.txt"