Declaring exception specifications in class hierarchy
#include <string>
#include <typeinfo>
class base {
public:
virtual void f() throw();
virtual void g(); // can throw anything
virtual void h() throw(std::string);
};
class derived : public base {
public:
virtual void f() throw(); // OK: same as base
virtual void g() throw(int); // OK: subset of base
//virtual void h() throw(int); // Error: int not in base
};
class more : public derived {
public:
//virtual void f(); // Error: can throw anything
virtual void g() throw(); // OK
};Demonstrating stack unwinding
#include <iostream>
using std::cout;
using std::endl;
#include <stdexcept>
using std::runtime_error;
void f3() throw ( runtime_error )
{
cout << "In f 3" << endl;
throw runtime_error( "runtime_error in f3" );
}
void f2() throw ( runtime_error )
{
cout << "f3 is called inside f2" << endl;
f3();
}
void f1() throw ( runtime_error )
{
cout << "f2 is called inside f1" << endl;
f2();
}
int main()
{
try
{
cout << "f1 is called inside main" << endl;
f1();
}
catch ( runtime_error &error )
{
cout << "Exception occurred: " << error.what() << endl;
cout << "Exception handled in main" << endl;
}
return 0;
}f1 is called inside main
f2 is called inside f1
f3 is called inside f2
In f 3
Exception occurred: runtime_error in f3
Exception handled in main
Handling Derived-Class Exceptions
#include <iostream>
using namespace std;
class B {
};
class D: public B {
};
int main()
{
D derived;
try {
throw derived;
}
catch(B b) {
cout << "Caught a base class.\n";
}
catch(D d) {
cout << "This won"t execute.\n";
}
return 0;
}