Created
April 11, 2023 11:05
-
-
Save ajsb85/09c877dd4d19c3347eeb5672a6c4df4c to your computer and use it in GitHub Desktop.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| #include <stdio.h> | |
| #include <time.h> | |
| #include <sys/time.h> | |
| #include <unistd.h> | |
| #include <assert.h> | |
| static void set_time(void); | |
| static void get_time(void); | |
| int main(void) | |
| { | |
| set_time(); | |
| while (1) { | |
| get_time(); | |
| sleep(0.01); | |
| } | |
| } | |
| // 02:37:01.086 | |
| char* asktime(const struct tm *timeptr) | |
| { | |
| static char result[26]; | |
| sprintf(result, "%.2d:%.2d:%.2d\n", | |
| timeptr->tm_hour, | |
| timeptr->tm_min, timeptr->tm_sec); | |
| return result; | |
| } | |
| static void set_time(void) | |
| { | |
| // Prepare the broken-down time. | |
| // See https://en.cppreference.com/w/c/chrono/tm | |
| struct tm initial_time = { | |
| .tm_year = 2022 - 1900, | |
| .tm_mon = 3 - 1, | |
| .tm_mday = 17 - 1, | |
| .tm_hour = 21, | |
| .tm_min = 35, | |
| .tm_sec = 0 | |
| }; | |
| // Convert to Unix time. | |
| // See https://en.cppreference.com/w/c/chrono/mktime | |
| time_t initial_unix_time = mktime(&initial_time); | |
| // Convert to 'struct timeval' | |
| struct timeval initial_timeval = { | |
| .tv_sec = initial_unix_time, | |
| .tv_usec = 0 | |
| }; | |
| // Set system time. | |
| // See https://linux.die.net/man/2/settimeofday | |
| int err = settimeofday(&initial_timeval, NULL); | |
| // assert(err == 0); | |
| printf("Time set to: %s", asctime(&initial_time)); | |
| } | |
| static void get_time(void) | |
| { | |
| // Get current time as 'struct timeval'. | |
| // See https://linux.die.net/man/2/gettimeofday | |
| struct timeval new_timeval; | |
| int err = gettimeofday(&new_timeval, NULL); | |
| assert(err == 0); | |
| // Extract Unix time | |
| time_t new_unix_time = new_timeval.tv_sec; | |
| int iMilliSec = new_timeval.tv_usec / 1000; | |
| int iMicroSec = new_timeval.tv_usec; | |
| // Convert to broken-down time | |
| // See https://en.cppreference.com/w/c/chrono/localtime | |
| struct tm new_time; | |
| localtime_r(&new_unix_time, &new_time); | |
| // 'new_time' now contains the current time components | |
| static char result[26]; | |
| sprintf(result, "%.2d:%.2d:%.2d.%.3d\n", | |
| new_time.tm_hour, | |
| new_time.tm_min, new_time.tm_sec,iMilliSec); | |
| printf("%s", result); | |
| } |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment