Set illegal indirection error? - c++

Question

I'm getting a "set illegal indirection error" but I can't figure out what I am doing wrong.
What I am trying to do is take input from input.txt file that has a form
string1 string2
string3 string4
etc.
And number the strings in ascending order without duplicates, then use them in some functions and store the values in struct StringInt. But I am getting this weird error and I don't know where to start fixing it.
struct StringInt {
std::string name; // associate name and number for each input string
int number;
};
int main(int argc, char* argv[]) {
tot_strings = 100;
std::string vert1, vert2;
std::set<std::string> inGraph(0, tot_strings); // this is the set in question
std::set<std::string>::iterator sit;
std::vector<StringInt> stringInts(tot_strings); // Edit: forgot to mention this initially
StringInt* si;
int icv1, icv2;
std::ifstream myfile2 ("input.txt");
if (myfile2.is_open()) {
while(myfile2 >> vert1 >> vert2) {
myfile2 >> vert1 >> vert2;
if (inGraph.find(vert1) != inGraph.end()) { // not sure if I do this correctly
icv1 = i++;
si->name = vert1;
si->number = icv1;
inGraph.insert(vert1); // here's the insert that might be
stringInts.push_back(*si); // causing of the error
}
else {
icv1 = si->number;
}
if (inGraph.find(vert2) != inGraph.end()) {
icv2 = i++;
si->name = vert1;
si->number = icv2;
inGraph.insert(vert2);
stringInts.push_back(*si);
}
else {
icv1 = si->number;
}
// use icv1 and icv2 as int inputs in functions below
}
Does what I have make sense and how can I go about fixing the "set illegal indirection error"?
Edited: included std::vector stringInts(tot_strings) that I had in my code but forgot to include in the example.