Reading/Writing several structs of unknown size to file C++

Question

I am wanting to make a book database to record what books I have read. So far, I have a structure for a book entry.

struct Entry
{
    string title;
    string author;
    int pages;
};

As you can see, the title and the author variables are of undetermined size. I would like to store several structures within one file, and then to read all those structures when I want to display the database.

How would I read/write several of these structures from a file? Would I have to have predetermined sizes? Please provide an example.

Answer 1

you could easily store it in a CSV-format the following way:

title_1,author_1,pages_1,title_2,author_2,pages_2,title_3,auth...

when reading back the file, then parse the file according to your separators and you have back your data.

edit : as @Mark Setchell suggested you shouldn't use ' , ' as a separator, because a comma might also be part of the title itself. instead you should use a more rare character as separator, which isn't used very often in possible book titles. some examples are ' ; ' ' | ' or ' # ' or even unprintable characters