C++ Compare 2 dates and check the minutes difference - c++

Question

Here's the thing:
A datetime access is created with C# using DateTime.Now. This datetime is passed through JSON to a C++ method. I'm using JsonCpp to handle the Json data, but I'm not sure how to handle when the data is a datetime.
I want to compare this datetime that I received with the actual datetime and check the minutes difference between this two (if the difference is on a interval that was defined).
If I convert the Json datetime to a string using JsonCpp I have this format:
2015-06-08T11:17:23.746389-03:00
So what I'm trying to do is something like this:
var d1 = oldAccess["Date"].ToString(); //Json datetime converted to a string
var d2 = actualAccess["Date"].ToString()
if((d2 - d1) < 20) { //Difference between the two dates needs to be less than 20 minutes
return true;
} else return false;
I'm new in C++, even looking for I don't discovered how to do this.

Answer 1

Well, I got it. Not the best way neither the pretty one, but it works since I know that the two dates were set on the same server and always comes in the same format \"2015-01-01T23:40:00.000000-03:00\"
Here's what I did:
int convertToInt(std::string number_str){
int number;
std::istringstream ss(number_str);
ss.imbue(std::locale::classic());
ss >> number;
return number;
}
time_t convertDatetime(std::string date_str) {
time_t rawtime;
struct tm date;
int year, month, day, hour, min, sec;
date_str.erase(std::remove_if(date_str.begin(), date_str.end(), isspace), date_str.end());
year = convertToInt(date_str.substr(1, 4));
month = convertToInt(date_str.substr(6, 2));
day = convertToInt(date_str.substr(9, 2));
hour = convertToInt(date_str.substr(12, 2));
min = convertToInt(date_str.substr(15, 2));
sec = convertToInt(date_str.substr(18, 2));
time(&rawtime);
localtime_s(&date, &rawtime);
date.tm_year = year - 1900;
date.tm_mon = month - 1;
date.tm_mday = day;
date.tm_hour = hour;
date.tm_min = min;
date.tm_sec = sec;
return mktime(&date);
}
bool isValidIntervalDatetime(std::string actualDatetime_str, std::string oldDatetime_str, int maxMinutesInterval) {
double maxSecondsInterval = 60 * maxMinutesInterval;
time_t actualDatetime = convertDatetime(actualDatetime_str);
time_t oldDatetime = convertDatetime(oldDatetime_str);
double secondsDiff = difftime(actualDatetime, oldDatetime);
return secondsDiff <= maxSecondsInterval;
}
int main(int argc, char* argv[])
{
auto maxMinutesInterval = 20;
auto actuaDatetime = JsonConverter::toString(actualAccess["Date"]); // \"2015-01-02T00:00:00.000000-03:00\"
auto oldDatetime = JsonConverter::toString(oldAccess["Date"]); // \"2015-01-01T23:40:00.000000-03:00\"
if (isValidIntervalDatetime(actuaDatetime, oldDatetime, maxMinutesInterval){
//do something
}
}