How to convert a time into epoch time?

Question

Say I have a specific instant in time where I know the hour, minute, day, second, month, year, etc; how can I convert this epoch time (seconds since 1970)?

I can\'t

Answer 1

Sample code to convert date string in some format to unix epoch time.

struct tm tm;
double dateInEpoch;

if (strptime("06 Jul 2022", "%d %b %Y", &tm)) {
    time_t curTime;
    struct tm * timeinfo;
                
    time(&curTime );
    timeinfo = localtime(&curTime);
                
    timeinfo->tm_year = tm.tm_year
    timeinfo->tm_mon = tm.tm_mon;
    timeinfo->tm_mday = tm.tm_mday;
        
    dateInEpoch = mktime( timeinfo );
}

For date format, please visit http://www.cplusplus.com/reference/ctime/strftime/

To test epoch date, visit https://www.epochconverter.com