Generating field-level variables inside of a function

This is actually a two part question, one being generating field-level variables inside of a function and the other being how to generate new variable names.

So below, say I have a string called str and an int n. I want to combine str (str literally, not the name of the string) and the value of n to create a new string, say str0, str1, etc. Now, I figured I could do this by using a print function to generate code, but I don't want to do it that way.

The other question would be how to generate field level variables (not static, but variables that only exist for that particular instance) within a subroutine of the class.

class VarGen
{	
	int n;
	string varname;
	
	string gen ()
	{
		string strn;
		//code to convert n to a string called strn;
		
		//combine varname and strn to generate a new string ??

                //Also, code to generate a field level variable, something like "field int q;"

                return //generated string name

	}
	
} vg;

int main()
{
	vg.n = 0;
	
	vg.string = "hello";
	
	vg.gen();
	
	return 0;
}