In C++, the no-argument constructors for all superclasses and member variables are called for you, before entering your constructor. If you want to pass them arguments, there is a separate syntax for this called "constructor chaining", which looks like this:
class Sub : public Base{ Sub(int x, int y) : Base(x), member(y) { } Type member;};If anything run at this point throws, the bases/members which had previously completed construction have their destructors called and the exception is rethrown to to the caller. If you want to catch exceptions during chaining, you must use a function try block:
class Sub : public Base{ Sub(int x, int y) try : Base(x), member(y) { // function body goes here } catch(const ExceptionType &e) { throw kaboom(); } Type member;};In this form, note that the try block is the body of the function, rather than being inside the body of the function; this allows it to catch exceptions thrown by implicit or explicit member and base class initializations, as well as during the body of the function. However, if a function catch block does not throw a different exception, the runtime will rethrow the original error; exceptions during initialization cannot be ignored.