Time Management
Use these functions to get the current time and convert, adjust, and store it as necessary. The current time is the system time.
The _ftime and localtime routines use the TZ environment variable. If TZ is not set, the run-time library attempts to use the time-zone information specified by the operating system. If this information is unavailable, these functions use the default value of PST8PDT. For more information on TZ, see _tzset; also see _daylight, timezone, and _tzname.
Time Routines
| Function | Use |
| asctime, _wasctime | Convert time from type structtm to character string |
| clock | Return elapsed CPU time for process |
| ctime, _wctime | Convert time from type time_t to character string |
| difftime | Compute difference between two times |
| _ftime | Store current system time in variable of type struct _timeb |
| _futime | Set modification time on open file |
| gmtime | Convert time from type time_t to struct tm |
| localtime | Convert time from type time_t to struct tm with local correction |
| mktime | Convert time to calendar value |
| _strdate, _wstrdate | Return current system date as string |
| strftime, wcsftime | Format date-and-time string for international use |
| _strtime, _wstrtime | Return current system time as string |
| time | Get current system time as type time_t |
| _tzset | Set external time variables from environment time variable TZ |
| _utime, _wutime | Set modification time for specified file using either current time or time value stored in structure |
Note In all versions of Microsoft C/C++ except Microsoft C/C++ version 7.0, and in all versions of Microsoft Visual C++, the time function returns the current time as the number of seconds elapsed since midnight on January 1, 1970. In Microsoft C/C++ version 7.0, time returned the current time as the number of seconds elapsed since midnight on December 31, 1899.