C++ TUTORIALS - C++ Date & Time
C++ Date & Time
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SN | Function & Purpose |
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1 | time_t time(time_t *time); This returns the current calendar time of the system in number of seconds elapsed since January 1, 1970. If the system has no time, .1 is returned. |
2 | char *ctime(const time_t *time); This returns a pointer to a string of the form day month year hours:minutes:seconds year\n\0. |
3 | struct tm *localtime(const time_t *time); This returns a pointer to the tm structure representing local time. |
4 | clock_t clock(void); This returns a value that approximates the amount of time the calling program has been running. A value of .1 is returned if the time is not available. |
5 | char * asctime ( const struct tm * time ); This returns a pointer to a string that contains the information stored in the structure pointed to by time converted into the form: day month date hours:minutes:seconds year\n\0 |
6 | struct tm *gmtime(const time_t *time); This returns a pointer to the time in the form of a tm structure. The time is represented in Coordinated Universal Time (UTC), which is essentially Greenwich Mean Time (GMT). |
7 | time_t mktime(struct tm *time); This returns the calendar-time equivalent of the time found in the structure pointed to by time. |
8 | double difftime ( time_t time2, time_t time1 ); This function calculates the difference in seconds between time1 and time2. |
9 | size_t strftime(); This function can be used to format date and time a specific format. |
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struct tm { int tm_sec; // seconds of minutes from 0 to 61 int tm_min; // minutes of hour from 0 to 59 int tm_hour; // hours of day from 0 to 24 int tm_mday; // day of month from 1 to 31 int tm_mon; // month of year from 0 to 11 int tm_year; // year since 1900 int tm_wday; // days since sunday int tm_yday; // days since January 1st int tm_isdst; // hours of daylight savings time }ADVERTISEMENTSCurrent date and time:
#include <iostream> #include <ctime> using namespace std; int main( ) { // current date/time based on current system time_t now = time(0); // convert now to string form char* dt = ctime(&now); cout << "The local date and time is: " << dt << endl; // convert now to tm struct for UTC tm *gmtm = gmtime(&now); dt = asctime(gmtm); cout << "The UTC date and time is:"<< dt << endl; }Format time using struct tm:
#include <iostream> #include <ctime> using namespace std; int main( ) { // current date/time based on current system time_t now = time(0); cout << "Number of sec since January 1,1970:" << now << endl; tm *ltm = localtime(&now); // print various components of tm structure. cout << "Year: "<< 1900 + ltm->tm_year << endl; cout << "Month: "<< 1 + ltm->tm_mon<< endl; cout << "Day: "<< ltm->tm_mday << endl; cout << "Time: "<< 1 + ltm->tm_hour << ":"; cout << 1 + ltm->tm_min << ":"; cout << 1 + ltm->tm_sec << endl; }