Exception

• Exception type

C++

class VectorIndexError
{
public:
  VectorIndexError(int v):m_badValue(v){}
  VectorIndexError({}
  void diagnostic(){
    cout<<"index"<< m_badValue <<"out of range!";
  }
private:
  int m_badValue;
}

C++

throw <<something>>

throw raises exception.

• Try blocks can select type of exceptions

C++

try {...}
  catch {...}

C++

try{
  func();
} catch(VIE v){ // take a single argument
  cout<< "8\n";
} catch (...){ // others
  cout<< "7\n";
}

it can re-raise exceptions

• Hierarchy of exception types

C++

class MathErr{
  ...
  virtual void diagnostic();
};

class OverflowErr : public MathErr {...}
class UnderflowErr : public MathErr {...}

a catch of parent Exception Type can catch its child type.

C++

try{
  throw VIEE(idx);
}catch (VIE v){
  cout<< "7\n";
}catch (...){
  cout<< "6\n";
}
// output 7

try{
  throw VIEE(idx);
}catch (VIEE v){
  cout<< "8\n";
}catch (VIE v){
  cout<< "7\n";
}catch (...){
  cout<< "6\n";
}
// output 8

try{
  throw VIEE(idx);
}catch (VIE v){
  cout<< "8\n";
}catch (VIEE v){ // this expression is useless
  cout<< "7\n";
}catch (...){
  cout<< "6\n";
}
// output 8

• Standard Library Exception

• Failure in C'tor