I think there are quite a few mistakes in your code :
(1) InventoryInfo class does not have any member func named WriteToFile !
vector<InventoryInfo> iInfo; //Creates an object...vector of strings...
So, use it like :
(2) Vector does not have a member named c_str() !! Strings have it.
void WriteToFile(vector<InventoryInfo> iInfo)
fstream OutFile(iInfo.c_str(), ios::out);
vector<InventoryInfo>::iterator AccessInventory; //Sets up an iterator...
for( AccessInventory = iInfo.begin() ; AccessInventory != iInfo.end() ; ++AccessInventory)
I really don't understand what you wanted to do here !
Why did you need to pass "Success" into this func ?? Did you intend it to write to a file named "Success" ??
In that case, change the line to
fstream OutFile("Success", ios::out);
and don't pass "Success" as an argument, rather pass iInfo as the argument.