Add milliseconds to timeval C++

Question

With the code beneath I can get the current time in milliseconds. Now I want to add milliseconds to the systemtime. Any hints?

#include <stdio.h>
#include <sys/time.h>

int main (int argc, char** argv) {
    struct timeval time;
    gettimeofday (&time, NULL);

    long systemtime = time.tv_sec*1000L + time.tv_usec/1000L;

     printf("Time in milliseconds: %ld milliseconds\n", systemtime);
     //sample output: 1492592522106

     return 0;
}

EDIT: SOLVED

#include <stdio.h>
#include <sys/time.h>

int main (int argc, char** argv) {
    struct timeval time;
    gettimeofday (&time, NULL);

    printf("Time in milliseconds: %ld milliseconds\n", time.tv_sec*1000L + 
    (time.tv_usec/1000L));
    printf("Time in milliseconds+300: %ld milliseconds\n", time.tv_sec*1000L 
    + (time.tv_usec/1000L+300));
    printf("usec: %ld", time.tv_usec/1000L);

    return 0;
}

output:

Time in milliseconds: 1492595580965 milliseconds (Wed, 19 Apr 2017 09:53:00.965 GMT)
Time in milliseconds+300: 1492595581265 milliseconds (Wed, 19 Apr 2017 09:53:01.265 GMT)
usec: 965

Possible duplicate of [how to calculate milliseconds using timeval structure?](http://stackoverflow.com/questions/18650057/how-to-calculate-milliseconds-using-timeval-structure) — Gonras Karols, Apr 19 '17 at 09:12
I have the current time in milliseconds already. Now I want to ADD for example 300ms to the current time (systemtime in code). — Janoshh, Apr 19 '17 at 09:17
"add milliseconds to the systemtime" Please explain what exact *effect* you want it to have. — n. m. could be an AI, Apr 19 '17 at 09:26
For example the current time is 09:10:53.000. I want to add 300ms to it, so the result is: 09:10:53.300 — Janoshh, Apr 19 '17 at 09:39

score 4 · Answer 1 · answered Apr 19 '17 at 09:39

4

You can use std::chrono library to perform this task. Following code snippet will help you with this,

auto now = std::chrono::system_clock::now().time_since_epoch();
auto t100ms = std::chrono::milliseconds(100);
auto time = now + t100ms;
std::cout << std::chrono::duration_cast<std::chrono::milliseconds>(time).count();

answered Apr 19 '17 at 09:39

shofee

2,079
13
30

std::chrono is only available for C++11 and higher. You should mention that in your answer. – Alex Oct 11 '17 at 12:18
std::chrono needs to be included: `#include ` – Alex Oct 11 '17 at 12:19

score -3 · Answer 2 · answered Apr 19 '17 at 09:21

-3

Did you try adjtime()? . http://man7.org/linux/man-pages/man3/adjtime.3.html

answered Apr 19 '17 at 09:21

mr3d

1
1

1

Not related. `adjtime()` is used in order to adjust the systemclock ... op only wants to modify a variable of type `timeval`. – Alex Oct 11 '17 at 12:53

Add milliseconds to timeval C++

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