cpp/chrono/c/mktime

Converts local calendar time to a time since epoch as a object. and are ignored. The values in are permitted to be outside their normal ranges.

A negative value of causes  to attempt to determine if Daylight Saving Time was in effect.

If the conversion is successful, the object is modified. All fields of are updated to fit their proper ranges. and are recalculated using information available in other fields.

Return value
Time since epoch as a std object on success or if  cannot be represented as a std object.