Can lambda functions be recursive?
c++, c++11, lambda, recursion
Solution
Yes, they can. Starting with C++23 you can use the explicit this parameter:
auto factorial = [](this auto self, int i)
{
return (i == 1) ? 1 : i * self(i - 1);
};
With previous C++ standards, you can store the lambda in a variable and reference that variable (although you cannot declare the type of that variable as `auto`, you would have to use an `std::function` object instead). For instance:
std::function<int (int)> factorial = [&] (int i)
{
return (i == 1) ? 1 : i * factorial(i - 1);
};
Problem
Possible Duplicate: Recursive lambda functions in c++0x Here is a plain old recursive function: ``` int fak(int n) { return (n <= 1) ? 1 : n * fak(n - 1); } ``` How would I write such a recursive function as a lambda function? ``` [](int n) { return (n <= 1) ? 1 : n * operator()(n - 1); } // error: operator() not defined [](int n) { return (n <= 1) ? 1 : n * (*this)(n - 1); } // error: this wasn't captured for this lambda function ``` Is there any expression that denotes the current lambda so it can call itself recursively?