As far as I know, there is no such function in any of the standard C++
libraries. Either the book you are reading provides its definition, or you'll have to implement it yourself. For reading from files, you'll need either methods from fstream
(alternatively, you may use the old style plain C cstdio
If you're unsure about how to do this, I strongly recommend that you familiarise yourself with the basics of C++
(the sticky thread
here in the programming section has a lot of resources for learning C
) before continuing with your book.