What does the second parameter mean in this signature?

Question

std::vector<int> interpret(const std::string &src, const std::vector<int> &input = {});

I understand everything about the signature except setting the reference input to {}. What does that mean?

Answer 1

The = introduces a default value for the parameter... {} in this case indicates an empty vector. Consequently, you can invoke the function with one argument, and input will be empty.