Convert Long of Unix Epoch Timestamp to Real Date/Time - c++

Question

I have attempted to find an answer to this question but the sources I have found do not properly convert the time. Originally I have the timestamp in a string as I am getting the timestamp from a .json web scraping program but want to convert it to a readable date/time. My latest attempt to do the conversion was to convert the string into a long and the long to time_t and then use strftime() but that does not produce the correct answer.
Here is the code where I converted the string to a long and then to time_t and then used strftime()
std::string timeStampToRead(const time_t rawtime)
{
struct tm *dt;
char buffer [30];
dt = localtime(&rawtime);
strftime(buffer, sizeof(buffer), "%m%d %H%M", dt);
return std::string(buffer);
}
int main()
{
std::string epochT = "1604563859000";
long e = atol(epochT.c_str());
const time_t rawtime = (const time_t)e;
std::string time = timeStamptToRead(rawtime);
return 0;
}
The result of this code is 0808 1703
I also attempted to do something very similar to above but changed timeStampToRead to the following
std::string timeStampToRead(const time_t rawtime)
{
struct tm *dt;
char buffer [30];
dt = localtime(&rawtime);
return asctime(dt);
}
This returns Mon Aug 8 17:03:20 which is also incorrect
The correct answer should be Thursday, November 5, 2020 8:10:59 UTC or Thursday, November 5, 2020 1:10:59 locally (not necessarily in that exact format just the correct month, day, and time is important)
I have tested the outcome of converting the string to a long and that is working correctly so I am thinking the error is either in converting the long to time_t or the process of using the time_t to get a readable format of the time. Of the two options, I think it is more likely the conversion from long to time_t is the issue but can't find another way to do the conversion.
I was hoping there was an easy way to directly take the string and convert it but I cannot find any information on that anywhere so that is why I resulted to converting the string to long and then to time_t. Basically, I can't figure out how to convert a string or long unix epoch timestamp to time_t to convert it to a readable format, or at least that is where I am assuming the error is. If anyone could point me in the right direction to get this conversion code working I would greatly appreciate it.

Answer 1

After some further digging, I have found my error and determined the best route
std::string epochT = "1604563859000";
long e atol(epochT.c_str());
const time_t rawtime = e/1000;
struct tm * dt;
dt = localtime(&rawtime);
std::string readable = asctime(dt);
This code will be inside a for loop that iterates through vectors of strings so epochT will be dependent on the elements in the vector and the current element, but this works and outputs the correct answer of Thu Nov 5 01:10:59 2020 local time.