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Overview

This code snippet shows how to convert a date and time to a string. The easiest way to get this string is to use the library function asctime() from the <ctime> header. The returned string has the following format: "Www Mmm dd hh:mm:ss yyyy". Another possibility is to use the time_put template class from the <locale> header and use a custom formatting for the date and time string.

Note: In order to use this code, you need to install the Open C/C++ plug-in.

This snippet can be self-signed.

MMP file

The following libraries are required:

STATICLIBRARY   libcrt0.lib
 
LIBRARY  libstdcpp.lib
LIBRARY  libc.lib
LIBRARY  euser.lib

Source file

#include <iostream>
#include <string>
#include <sstream>
#include <locale>
#include <ctime>
 
using namespace std;
 
string datetime_to_string(const tm& time, const char* format) 
{
    stringstream datetime;
  
    // retrieve the time_put facet installed in the stream
    const time_put<char>& writer = 
      use_facet< time_put<char> >(datetime.getloc());
    
    int len = strlen(format);
    
    //formats the contents of the tm time into the output stream datetime
    if (writer.put(datetime, datetime, ' ', 
            &time, format, format + len).failed( )) 
        {
        throw runtime_error("formatting date time failed!");
        }
    
    return datetime.str();
}
 
int main( )
{
   string time_string;
   time_t time_now = time(NULL);
   struct tm * timeinfo;
   timeinfo = localtime (&time_now);
   
//-- using the library function asctime()   
 
   cout << "Current local time and date: " << endl 
        << asctime(timeinfo) << endl;
 
//-- using the own function datetime_to_string()   
   
   /* The list of % format specifiers:
     a              Abbreviated weekday name     
     A              Full weekday name            
     b              Abbreviated month name      
     B              Full month name             
     c              Date and time              
     d              Day of the month            
     H              Hour of the 24-hour day     
     I              Hour of the 12-hour day     
     j              Day of the year
     m              Month of the year
     M              Minutes after the hour      
     p              AM/PM indicator     
     S              Seconds after the minute     
     U              Week of the year (Sunday)
     w              Day of the week
     W              Week of the year (Monday)
     x              Date MM/DD/YY
     X              Time HH/MM/SS (24-hour)
     y              Year of the century
     Y              Year
     Z              Time zone name
   */
   
  try 
  {
    time_string = datetime_to_string(*timeinfo, "%A %B %d %H:%M:%S %Y");
    cout << time_string << endl;
    
    time_string = datetime_to_string(*timeinfo, "%Y/%m/%d %H:%M:%S");
    cout << time_string << endl;
    
    time_string = datetime_to_string(*timeinfo, "%x %X");
    cout << time_string << endl;    
  }
  catch (const exception& e)
  {
    cout << "Exception: " << e.what() << endl;
  }
 
  //getchar();
  
  return 0;  
}

Postconditions

The current date and time have been converted to four different formats and are shown on the screen.