Skip to Main Content
C++ Cookbook
book

C++ Cookbook

by D. Ryan Stephens, Christopher Diggins, Jonathan Turkanis, Jeff Cogswell
November 2005
Beginner to intermediate content levelBeginner to intermediate
594 pages
16h 23m
English
O'Reilly Media, Inc.
Content preview from C++ Cookbook

5.2. Formatting a Date/Time as a String

Problem

You want to convert a date and/or time to a formatted string.

Solution

You can use the time_put template class from the <locale> header, as shown in Example 5-4.

Example 5-4. Formatting a datetime string

#include <iostream>
#include <cstdlib>
#include <ctime>
#include <cstring>
#include <string>
#include <stdexcept>
#include <iterator>
#include <sstream>

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");
  }
  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;
}

Output of the program in Example 5-4 will resemble the following, depending on your local settings:

Sunday July, 24 2005 05:48PM
2005-07-24 17:48:11

Discussion

The time_put member function put uses a formatting string specifier like the C printf function format string. Characters are output to the buffer as they appear in ...

Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Start your free trial

You might also like

C++ System Programming Cookbook

C++ System Programming Cookbook

Onorato Vaticone

Publisher Resources

ISBN: 0596007612Supplemental ContentErrata Page