More Exceptional C++: 40 New Engineering Puzzles, Programming Problems, and Solutions

Difficulty: 5

C++ has nested classes, but not nested functions. When might nested functions be useful, and can they be simulated in C++?

1. What is a nested class? Why can it be useful?

2. What is a local class? Why can it be useful?

3. C++ does not support nested functions. That is, we cannot write something like

   // Example 33-3 // int f( int i ) { int j = i*2; int g( int k ) // not valid C++ { return j+k; } j += 4; return g( 3 ); }

   Demonstrate how it is possible to achieve the same effect in standard C++, and show how to generalize the solution.