Using vector.size() in a function?

[larrydavid]

Hi -

I am playing with a little program where I create a virtual population. So far, I've used vectors to assign the sex randomly. (vector[i] = randomsex); What I'd like to do now is count the total of my population by counting the combined of both sexes. I know I can do this using: vector.size() but I'd like to somehow do this in a function called population that returns the number so I can just call population().

Unfortunately, this doesn't work as the vector is not carried over into the function, so I'm not sure what I need to do next. Is this the kind of thing I should be doing as a class? If so, how would I achieve that?

Thanks!

[LB]

You will probably want to be doing it as classes. If you just want to get your code working you can pass the vector by reference.

What I would do is make a class to represent each person that contains their gender and name, age, etc. and then another class to contain a population, which just maintains an internal vector. Try using proper encapsulation (private member variables and public member functions) and such.

Here's another handy tip: use typedefs for your vector types to make your life easier:

typedef std::vector<Person> People_t; //People_t is the same as std::vector<Person>

People_t people; //is a vector of people

for(People_t::iterator it = people.begin(); it != people.end(); ++it)
{
    //iterates each person
}

People_t::size_t population_size = people.size(); //number of people