Time Manipulation Functions
| clock | Clock program |
| difftime | return difference between two times |
| mktime | Convert tm structure to time_t |
| time | Get current time |
Conversion Functions
| asctime | Convert tm structure to string |
| ctime | Convert time_t value to string |
| gmtime | Convert time_t to tm as UTC time |
| localtime | Convert time_t to tm as local time |
| strftime | Format time as string |
Macro Constants (macros)
| CLOCKS_PER_SEC | Clock ticks per second |
| NULL | Null pointer |
Types
| clock_t | Clock type |
| size_t | Unsigned integral type |
| time_t | Time type |
| struct tm | Time structure |