The load function begins much the same, except we open the file named file for reading instead.
When receiving data from the file we put it in the string file_contents.
The absence of arguments to the method o->read means that the reading should not end until the end of the file.
After having closed the file we initialize our database, i.e. the mapping records. Then we have to put file_contents into the mapping and we do this by splitting the string on newlines (cf. the split operator in Perl) using the division operator. Yes, that's right: by dividing one string with another we can obtain an array consisting of parts from the first. And by using a foreach statement we can take the string file_contents apart piece by piece, putting each piece back in its proper place in the mapping records.
void load(string file_name)
write("Failed to open file.\n");
string cmd, arg;