CODEWITHSUNDEEP
c++
JJ Jones
JJ Jones

Reputation: 101

Output time and date with fractional time without using C++11

I am trying to find a solution on outputting current date and time (with milliseconds) in the following format: 2018-01-28 15:51:02.159

This could be solved using using C++17 and chrono::floor<chrono::seconds> or C++11 std::chrono::duration_cast<std::chrono::seconds>

Unfortunately I cannot use C++17 or C++11 - are there any other not too advanced options out there? If not, I would appreciate some help in getting the formatting correct without fractional time, like this: 2018-01-28 15:51:02

Help is very much appreciated!

Upvotes: 1

Views: 179

Answers (2)

chickity china chinese chicken
chickity china chinese chicken

Reputation: 8047

Using localtime and this post Getting current time with milliseconds:

#include <time.h>
#include <cstdio>  // handle type conversions 
#include <sys/time.h>

int main (void) {

    timeval curTime;
    gettimeofday(&curTime, NULL);
    int milli = curTime.tv_usec / 1000;

    char buffer [80];
    strftime(buffer, 80, "%Y-%m-%d %H:%M:%S", localtime(&curTime.tv_sec));

    char currentTime[84] = "";
    sprintf(currentTime, "%s.%d", buffer, milli);
    printf("current date time: %s \n", currentTime);

    return 0;
}

outputs:

current date time: 2018-01-28 14:45:52.486

Upvotes: 1

Gilbert
Gilbert

Reputation: 3776

As C++ inherits it's time units from C a guaranteed solution is to fall back to the C library (can't remember seeing a pure C++ version... this keeps as much C++ as I can):

#include <iostream>
#include <iomanip>                // std::setw()...
#include <cstdlib>

#include <sys/time.h>             // gettimeofday() and friends


int main(void)
{
     struct timeval  tv;
     struct tm       local_tm;
     char            print_time[30];

     gettimeofday(&tv,NULL);
     localtime_r( &tv.tv_sec, &local_tm );
     strftime( print_time, sizeof print_time, "%Y-%m-%d %H:%M:%S.", &local_tm );


     std::cout << print_time  << std::setw(3) << std::setfill('0') << ( tv.tv_usec + 500 ) / 1000 << std::endl;

     return EXIT_SUCCESS;
}

You could of course skip strftime() by a series of setw() calls, but I think strftime() is cleaner.

Upvotes: 1

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