C/C++ :: Recursively Building Cons Cell Structure Via Recursive Descent

I'm currently working on a Scheme Interpreter written in C. I'm trying to create a cons cell structure via recursive descent parsing, except instead of just having the car and cons, I also have a field that holds the token that I receive from the lexical analyzer (which was provided to us). The struct for what I'm describing is as such:

typdef struct node node;
typedef node* list;
struct node {
char* symbol;
list car;
list cdr;
};

Thus a cons cell would be (with a node represented as [symbol][car][cdr]), [null][car][cdr], while a symbol would be [symbol][null][null].

In the top answer for a similar question on Stack Overflow, one of the suggestions was to put the tokens into a stack as the input is recursively parsed, and then from that stack input it into the cons cell structure.

This is something that I'm working towards now, as it is easier for me to understand and I already have implemented a stack in C before, but I know that I can just build the structure recursively, I'm just not sure how. The following is code that I have:

list s_expression() {
list local;
list temp;
if (strcmp(token, "(") == 0) {
strcpy(token, getToken());

[Code] .....

s_expression is supposed to return a pointer to a recursively built cons cell structure. I'm just having issues figuring out when to call getToken(), as I either call getToken in the wrong spot and unintentionally skip over a token, or I call getToken() when I'm done getting all of the tokens, thus causing my program to continue searching for a token from user input instead of continuing on with the rest of the program.

When should I be calling getToken()?

In addition, what would be better, recursively building the cons cell structure as you go through the user's input, or putting all of the tokens into a stack and then building the cons cell structure using that stack?

If needed, I can post the lexical analyzer that's been provided to us. Also, for S_expression(); showing up as S_exp<b></b>pression();, I'm not sure what happened there. I copied this post from my question on stack overflow.