What does '&' mean in C++?

Question

What does \'&\' mean in C++?

As within the function

void Read_wav::read_wav(const string &filename)
{

}

And what is its equiv

Answer 1

It's a reference, as others have said. In C, you'd probably write the function as something like

void read_wav(struct Read_wav* rw, const char* filename)
{

}