Usage of std::list::sort hangs my program

Question

I have a program in C++ that organizes a bunch of college courses I want to take. It does so by taking input from the console (with things like course code, description, etc.), organizing each course by major, then outputting it all to a nicely-formatted, easy-to-read HTML file. Later, I plan on thinning out the list with a lot of research.

I implement each course as an object, which is added to a list when I finish entering the info. When I'm finished with all the info, list::sort should sort each course by major and code (eg, CSE 380 comes after CSE 110, and both come before ECO 108). The formatting afterwards is easy.

To sort, I have to implement a simple function, because even though not doing so is technically valid, I get a weird-ass error, I guess due to no '<' operator for my Course class. My function looks like this;

bool courseCompare(Course course1, Course course2) { return course1.getCode() < course2.getCode(); }

Where the getCode() returns a small string that holds the course code in three-letter/digit format (like "AMS 401"). This is meant to facilitate alphabetical order, obviously.

I call the sort method like so;

all_the_courses.sort(courseCompare);

Where all_the_courses is a list.

However, whenever I used std::list, the program just stops. Doesn't crash, gives no output, just sits there not responding when I input anything and hit Enter. Any ideas?

Answer 1

OK, it seems like I was going about this the completely wrong way. Turns out my problem is something completely different (involving filestreams). I need to figure out what it is, but it's NOT the sorting; a simple cout (which I really should have used before) reveals that. Sorry, everyone!

Answer 2

You are passing the parameters to your comparison function by value, not reference, so it's possible that the error lies in your copy constructor. The usual way to write a comparison function is with const references which avoids copying the object altogether:

bool courseCompare(const Course &course1, const Course &course2)