Chapter 1. Boost.Optional

Fernando Luis Cacciola Carballal

Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

Introduction

This library can be used to represent 'optional' (or 'nullable') objects that can be safely passed by value:

optional<int> readInt(); // this function may return either an int or a not-an-int

if (optional<int> oi = readInt()) // did I get a real int
  cout << "my int is: " << *oi;   // use my int
else
  cout << "I have no int";