Classes and Conversion

Lecture 4 - Slide 22 : 40

Given a user defined type T, programmed via a class or struct:

It is possible to convert from some type S to type T via constructors in T

It is possible to convert from type T to some type S via conversion operators in T

Type conversion in general

In which cases are conversion operators necessary? (Why not use a constructor in S of parameter T)
- When converting to built in types
- We cannot program constructors (with a T parameter) in a built-in type S
Conversion operator syntax - such as conversion to type int from class T
- T::operator int () const {...}
- Not: int T::operator int () const {...}
- Thus, constructor-like syntax

  while (cin >> i)                   // Convert istream to bool or int.
     cout << i*2 << " " << endl;     // Done with conversion operator in istream.