C/C++ :: Reading In A String And Turning It To Int

I have a problem with transforming a string, for example

"13 + 19"

and store this in a list as seperate integers,

list = {13, 19};

and another list with the +, -, /:

list2 = {+};

this is my function:

int evaluate(char* formula, int* result) {
struct List *listofintegers = list_create(); //creates a list, this is the structure:
/*
struct ListNode {
int value;
struct ListNode* next;

[Code] ....

This is how i execute my function in my main.c:

int value;
evaluate("19 + 16", value);

This is what i get in my prompt:

I will also have to seperate the +, - and / in another list,

I don't even know how i can get my string when char* formula is given as an argument...