strftime formats a broken-down time as text by combining a destination buffer, a format string, and a struct tm value. It resembles printf, but uses date-and-time conversion specifications beginning with %. TAKEAWAY: choose the format string to control the textual representation. section 8.5
The interface
size_t strftime(char s[static 1], size_t max, const char format[static 1], struct tm const tm[static 1]); Here, s is the character array to fill, max limits the available size, format describes the representation, and tm supplies the broken-down time. For example, %Y selects the year, %m the month, and %d the day of the month; combining such specifications composes a date representation. section 8.5
