Formatting a Date/Time as a String - C++ Data Type

C++ examples for Data Type:time

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Description

Formatting a Date/Time as a String

Demo Code

#include <iostream>
#include <cstdlib>
#include <ctime>
#include <cstring>
#include <string>
#include <stdexcept>
#include <iterator>
#include <sstream>
#include <iostream>
#include <ctime>
#include <iomanip>
#include <codecvt>
using namespace std;

ostream& formatDateTime(ostream& out, const tm& t, const char* fmt) {
  const time_put<char>& dateWriter = use_facet<time_put<char>>(out.getloc());
  int n = strlen(fmt);
  if (dateWriter.put(out, out, ' ', &t, fmt, fmt + n).failed()) {
    throw runtime_error("failure to format date time");
  }// w  w  w  .  j  av  a2  s .c o  m
  return out;
}

string dateTimeToString(const tm& t, const char* format) {
  stringstream s;
  formatDateTime(s, t, format);
  return s.str();
}

tm now() {
  time_t now = time(0);
  return *localtime(&now);
}
int main()
{
  try {
    string s = dateTimeToString(now(), "%A %B, %d %Y %I:%M%p");
    cout << s << endl;
    s = dateTimeToString(now(), "%Y-%m-%d %H:%M:%S");
    cout << s << endl;
  }
  catch (...) {
    cerr << "failed to format date time" << endl;
    return EXIT_FAILURE;
  }
  return EXIT_SUCCESS;
}

Result

Date/time format specifiers

Specifier Description
a Abbreviated weekday name (e.g., Mon)
A Full weekday name (e.g., Monday)
b Abbreviated month name (e.g., Dec)
B Full month name (e.g., May)
c Complete date and time
d Day of the month (01-31)
H Hour (00-23)
I Hour (01-12)
j Day of the year (001-366)
m Month (01-12)
M Minutes (00-59)
p AM/PM designation
S Second, including up to two leap seconds
U Week number (00-53), with week 1 starting on the first Sunday
w Weekday (0-6), where Sunday is 0
W Week number (00-53), with week 1 starting on the first Monday
x Date in form MM/DD/YY
X Time in form HH/MM/SS with 24-hour clock
y Year within the current century (00-99)
Y Year
Z Time zone abbreviation, or empty if the system doesn't know the time zone

Converting from Boost date/time classes to a tm struct 

using boost::gregorian;
using boost::posix_time;

void dateToTmAux(const date& src, tm& dest) {
  dest.tm_mday = src.day();
  dest.tm_year = src.year() - 1900;
  dest.tm_mon = src.month() - 1;
}

void ptimeToTmAux(const ptime& src, tm& dest) {
  dest.tm_sec = src.seconds();
  dest.tm_min = src.minutes();
  dest.tm_hour = src.hours();
  dateToTmAux(src.date(), dest);
}


tm ptimeToTm(const ptime& t) {
  tm ret = tm();
  ptimeToTmAux(t, ret);
  return ret;
}

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