C++17 STL Cookbook

How to do it...

We will implement a program that opens a file (which might fail), and then we'll read an integer out of it (which might fail, too). We do this with activated exceptions and then we see how we can handle those:

1. First, we include some headers and declare that we use the std namespace:

      #include <iostream>      #include <fstream>      #include <system_error>      #include <cstring>            using namespace std;

2. If we want to use stream objects with exceptions, we have to enable them first. In order to get a file stream object to throw an exception if the file we are letting it access does not exist, or if there are parsing errors, we need to set some fail bits in an exception mask. If we do something afterward that fails, it will trigger an exception. ...