Insert object in c++ list - c++

Question

I have the follow program in c++. The objective is receive some logs (that came from filedata variable), parse the logs, and save them to object list.
The part to do the parse its working good. But i have a problem when i iterate the parsed vector and try to save some elements to the list. I can get the elements (for example: elements.at(0) i get the first column (timestamp) but when i save to my list, we save two times the log (in this case the filedata only have two logs), but we save two time the SAME log.
My cpp program:
#include <iostream>
#include <sstream>
#include <string>
#include <vector>
#include <iterator>
#include <list>
class UserLogRecord
{
public:
std::string timestamp;
std::string id;
std::string name;
std::string data;
};
std::vector<std::string> explode(std::string const & s, char delim)
{
std::vector<std::string> result;
std::istringstream iss(s); // sequence of characters
for (std::string token; std::getline(iss, token, delim); )
{
result.push_back(std::move(token)); //transfer token to vector
}
return result;
}
int main()
{
const char* filedata =
"1496843100;2017-06-07 13:45:00;000002D8;2600;user1\n"
"9999999999;2017-06-07 13:45:00;000002D9;2800;user2";
std::vector<std::string> lines = explode(filedata,'\n');
std::list<UserLogRecord* > userLogRecords;
UserLogRecord* userLogRecord = new UserLogRecord;
//vector
for(int i = 0; i < lines.size(); i++)
{
std::vector<std::string> elements = explode(lines[i], ';');
userLogRecord->timestamp = elements.at(0);
userLogRecord->id = elements.at(2);
userLogRecord->name = elements.at(4);
userLogRecord->data = elements.at(3);
userLogRecords.push_back(userLogRecord);
}
//list of logs
std::list<UserLogRecord* >::const_iterator itLog = userLogRecords.begin();
while (itLog != userLogRecords.end())
{
std::cout << '\n' + (*itLog)->timestamp + '\n';
std::cout << (*itLog)->id + '\n';
std::cout << (*itLog)->name + '\n';
std::cout << (*itLog)->data + '\n';
++itLog;
}
return 0;
}
Output (when iterate the list):
9999999999
000002D9
user2
2800
9999999999
000002D9
user2
2800
Expected output:
1496843100
000002D8
user1
2600
9999999999
000002D9
user2
2800
My program save two logs (this part is 'good', i only have two logs) but its save always the same (curiously it is the last log)

Answer 1

You are only using one UserLogRecord and simply modifying the data instead of adding a new element in the list.
std::list::push_back is adding a copy of a pointer to UserLogRecord which remains the same for all the iterations of the loop. The same pointer is pushed multiple times in the list and therefore all elements have the same data.
The following code would fix the issue. A new UserLogRecord is created for each iteration. You must however remember to free the allocated memory with delete when you don't need it anymore.
//vector
for(int i = 0; i < lines.size(); i++)
{
UserLogRecord* userLogRecord = new UserLogRecord;
std::vector<std::string> elements = explode(lines[i], ';');
userLogRecord->timestamp = elements.at(0);
userLogRecord->id = elements.at(2);
userLogRecord->name = elements.at(4);
userLogRecord->data = elements.at(3);
userLogRecords.push_back(userLogRecord);
}