How to convert Datetime to Unix timestamp in Ada

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    with Ada.Calendar;
    with Ada.Text_IO;
    
    procedure Simple_Date_To_Unix_Timestamp is
        -- The Unix epoch starts on January 1, 1970
        Epoch : constant Ada.Calendar.Time := Ada.Calendar.Time_Of(1970, 1, 1);
    
        -- Example date: August 24, 2023, 00:00:00
        Specific_Time : Ada.Calendar.Time := Ada.Calendar.Time_Of(2023, 8, 24, 0, 0, 0.0);
    
        -- Calculate the difference in seconds
        Unix_Timestamp : constant Integer := Integer(Ada.Calendar.Seconds(Specific_Time - Epoch));
    
    begin
        -- Output the Unix timestamp
        Ada.Text_IO.Put_Line("Unix Timestamp: " & Integer'Image(Unix_Timestamp));
    end Simple_Date_To_Unix_Timestamp;

Output:

Unix Timestamp: 1692835200;

Example only. There may be multiple ways to perform this operation.

Code Explanation

This Ada code calculates the Unix timestamp for a specific date (eg. August 24, 2023, 00:00:00).
It first imports the Ada.Calendar and Ada.Text_IO packages. The code defines the Unix epoch (January 1, 1970) using Ada.Calendar.Time_Of. Then, it assigns the target date (2023-08-24) to the variable Specific_Time and calculates the difference in seconds between this date and the epoch using the Seconds() function. This difference is converted into an integer to represent the Unix timestamp.
Finally, the program prints the resulting Unix timestamp to the console using Ada.Text_IO.Put_Line.

Convert Unix timestamp to Date in Ada

Other useful Ada date functions

Function	Description	Example
`Clock`	Returns the current date and time as a value of type `Ada.Calendar.Time`.	`Clock` returns 2023-08-28T12:00:00Z
`Year (Time)`	Returns the year of a given `Time` value from `Ada.Calendar.Time`.	`Year(Clock)` returns 2023
`Month (Time)`	Returns the month (1-12) of a given `Time` value.	`Month(Clock)` returns 8 for August.
`Day (Time)`	Returns the day of the month (1-31) of a given `Time` value.	`Day(Clock)` returns 28 for the 28th of August.
`Second (Time)`	Returns the second part of a `Time` value (0-59).	`Second(Clock)` returns 12 for 12 seconds past the minute.
`Split (Time, Year, Month, Day, Seconds)`	Splits a `Time` value into its component parts: year, month, day, and seconds.	`Split(Clock, Y, M, D, S)` sets Y=2023, M=8, D=28, S=12
`Time_Of (Year, Month, Day, Seconds)`	Returns a `Time` value constructed from the provided year, month, day, and seconds.	`Time_Of(2023, 8, 28, 12)` returns 2023-08-28T12:00:00Z
`Time_Zones`	Provides timezone information for adjusting local and UTC times.	`Ada.Calendar.Time_Zones` can be used to handle time zone conversions.

Current Unix Timestamp SECONDS SINCE JAN 01 1970

Current UTC Time

2025-08-20