C++ stl, functions with no return type

Question

template<typename _Tp1>
operator auto_ptr_ref<_Tp1>() throw()
{ return auto_ptr_ref<_Tp1>(this->release()); }

template<typename _Tp1>
operator auto_ptr<_Tp1>() throw()
{ return auto_ptr<_Tp1>(this->release()); }

I found definition of this two methods in stl class auto_ptr.

Can somebody explain me please, how functions other then constructors have no return type ?

Answer 1

Because they are implicit conversion operators that return auto_ptr_ref<_Tp1> and auto_ptr<_Tp1> respectively. These themselves serve as return-type declarations.

Answer 2

Conversion operators to type auto_ptr_ref and auto_ptr

n3337 12.3.2/1

A member function of a class X having no parameters with a name of the form

conversion-function-id: operator conversion-type-id

conversion-type-id: type-specifier-seq conversion-declaratoropt

conversion-declarator: ptr-operator conversion-declaratoropt

specifies a conversion from X to the type specified by the conversion-type-id .