When is a function try block useful?

Question

I\'m wondering when programmers use function try blocks. When is it useful?

void f(int i)
try
{
   if ( i  < 0 ) 
      throw \"less than zero\";
   std::         


        

Answer 1

It might be useful if you want to catch exceptions from constructor's initializer.

However, if you do catch exception in constructor that way, you have to either rethrow it or throw new exception (i.e. you cannot just normally return from constructor). If you do not rethrow, it just happens implicitly.

#include 

class A
{
public:
  A()
  try {
    throw 5;
  }
  catch (int) {
    std::cout << "exception thrown\n";
    //return; <- invalid
  }
};

int main()
{
  try {
    A a;
  }
  catch (...) {
    std::cout << "was rethrown";
  }
}