Question

How can I find the current depth inside a recursive function in C++ without passing in the previous level? i.e. is it possible to know how many times the function was called without using a parameter to keep track of the level and passing that number in as a parameter each time the function is called?

For example my recursive function looks like this:

DoSomething(int level)
{
  print level;
  if (level > 10)
    return;
  DoSomething(++level);
}

main
{
  DoSomething(0);
}

Answer 1

Building on the answer already given by JoshD:

void recursive() 
{ 
    static int calls = 0;
    static int max_calls = 0;
    calls++;
    if (calls > max_calls)
        max_calls = calls;

    recursive();

    calls--;
}

This resets the counter after the recursive function is complete, but still tracks the maximum depth of the recursion.

I wouldn’t use static variables like this for anything but a quick test, to be deleted soon after. If you really need to track this on an ongoing basis there are better methods.