MSecPerDay
MSecPerDay = 86400000
Example
function DaysToMilliseconds(const Days: Integer): Int64;
begin
Result := Int64(Days) * MSecPerDay;
end;
Usage
MSecPerDay defines a nominal 24-hour day as 86,400,000 milliseconds, with important signed 32-bit scaling limits.
Overflow boundary
The constant itself fits signed 32-bit Integer. Multiplication by 24 produces 2,073,600,000 and still fits; multiplication by 25 produces 2,160,000,000 and exceeds 2,147,483,647. Ensure an operand is Int64 before multiplication, as in the example. Casting only after a LongInt multiplication is too late.
A local civil day can contain 23 or 25 elapsed hours across daylight-saving transitions. Leap seconds are also outside ordinary Velox TDateTime arithmetic. Use calendar functions for civil dates and a defined UTC/elapsed-time contract for instants.
Additional Technical Info
The modified PascalScript Classes compiler registers MSecPerDay from Delphi SysUtils as a signed LongInt. It is exactly 24 * 60 * 60 * 1000 nominal milliseconds. The published spelling is singular MSec, while Delphi source also describes the underlying RTL name as MSecsPerDay.
The value is useful for unit conversion of elapsed durations and timestamp fields whose contract explicitly uses nominal milliseconds. It is not a TDateTime day value and must not be added directly to one.
Related Code Library entries
- SecsPerDay - nominal seconds per day.
- EIGHT_HOUR_MILL - nominal eight-hour millisecond interval.
- Int64 - safe storage for scaled durations.
External references
- Embarcadero System.SysUtils - declaring Delphi unit.
- Free Pascal MSecsPerDay - compatible constant and formula.