title: Initialising variables in C++
body: <p>I want to initialise a lot of variables (doubles and ints mostly, but some vectors as well), which will then be passed into lots of functions. What is the best way to initialise these?</p>
  
  <p>I could initialise them all in the main function, this just feels a little messy, and ideally I wanted to create a separate function to initialise them in. I want to try and keep the main function as empty as I can. However, I then have the issue of not being able to return them. </p>
  
  <p>Is there a proper way of doing this? I've heard of constructors, but I'm not entirely sure what they're used for, and whether or not they're something that I should be looking at here.</p>