Simulating nested functions in C++

Question

In C the following code works in gcc.

int foo( int foo_var ) {  /*code*/   int bar( int bar_var )     {     /*code*/     return bar_var;   }   return bar(foo_var); } 

How can I achieve the same functionality of nested functions in C++ with the gcc compiler? Don't mind if this seems like a beginner question. I am new to this site.

Answer 1

Local functions are not allowed in C++, but local classes are and function are allowed in local classes. So:

int foo( int foo_var ) {  /*code*/   struct local    {     static int bar( int bar_var )       {       /*code*/       return bar_var;     }   };   return local::bar(foo_var); } 

In C++0x, you would also have the option of creating a functor using lambda syntax. That's a little more complicated in C++03, but still not bad if you don't need to capture variables:

int foo( int foo_var ) {  /*code*/   struct bar_functor   {     int operator()( int bar_var )       {       /*code*/       return bar_var;     }   } bar;   return bar(foo_var); } 

Answer 2

Turn your function into a functor as Herb Sutter suggests in this article