C++ :: How To Tell Function Which Part Of Struct To Use

Say I have a structure defined as such:

struct data{
char c;
int x;
};

And I want to create a function to print either c or x. However, I don't want to just use a switch or something to figure this out, I want to reference which part I'm outputting.

Now here's the twist

vector<data> dataList;

I need to access element x or c in the vector, but all I pass is the vector and which element, so that I might have something like:

void (vector<data> x, DataType i){
cout << x[0].i;
}

So now, if I pass either x or c (someway), I can output one of them.