How convert string to datetime c++? - c++

Question

string s = v[2];
string result = s.substr(s.find_last_of("modify=") + 1, 14);
cout << result;//output MDTM boost.txt 20150911115551
i want convert like this YYYY-MM-DD HH:MM

Answer 1

To access date and time related functions and structures, you would need to include header file in your C++ program.
There are four time-related types: clock_t, time_t, size_t, and tm. The types clock_t, size_t and time_t are capable of representing the system time and date as some sort of integer.
The structure type tm holds the date and time in the form of a C structure having the following elements:
struct tm {
int tm_sec; // seconds of minutes from 0 to 61
int tm_min; // minutes of hour from 0 to 59
int tm_hour; // hours of day from 0 to 24
int tm_mday; // day of month from 1 to 31
int tm_mon; // month of year from 0 to 11
int tm_year; // year since 1900
int tm_wday; // days since sunday
int tm_yday; // days since January 1st
int tm_isdst; // hours of daylight savings time
}
Considering that you have the data string in the following format "YYY-MM-DD HH:MM:SS", the subsequent code below show how to convert the string in a date structure:
#include <iostream>
#include <ctime>
#include <string.h>
#include <cstdlib>
using std::cout;
using std::endl;
int main(int argc, char* argv[])
{
char date[] = "2012-05-06 21:47:59";
tm *ltm = new tm;
char* pch;
pch = strtok(date, " ,.-:");
ltm->tm_year = atoi(pch); //get the year value
ltm->tm_mon = atoi(strtok(NULL, " ,.-:")); //get the month value
ltm->tm_mday = atoi(strtok(NULL, " ,.-:")); //get the day value
ltm->tm_hour = atoi(strtok(NULL, " ,.-:")); //get the hour value
ltm->tm_min = atoi(strtok(NULL, " ,.-:")); //get the min value
ltm->tm_sec = atoi(strtok(NULL, " ,.-:")); //get the sec value
// print various components of tm structure.
cout << "Year: "<< ltm->tm_year << endl;
cout << "Month: "<< ltm->tm_mon<< endl;
cout << "Day: "<< ltm->tm_mday << endl;
cout << "Time: "<< ltm->tm_hour << ":";
cout << ltm->tm_min << ":";
cout << ltm->tm_sec << endl;
delete ltm;
return 0;
}
Output:
Year: 2012
Month: 5
Day: 6
Time: 21:47:59