The topic for this chapter is Date and Time. Deceptively simple, handling dates and times in the context of leap years, across time zones and daylight savings and other such phenomena make this extremely complicated. In a projectlet or 2, we will explore some problems and thus exercise the predefined libraries of the language.
Convert Date and Time between internal and Printable formats
Arithmetic with Date, Time and Duration
Given a date of birth argument, compute and printout the age, details of the 50th, 60th and other significant birthdays. Leap years should be handled appropriately.
~/bin/bdayBday.P1
Date of Birth 1986-04-01 06:00:01
Day of the Week TUESDAY
Age (days) 14191
(years) 38
Birthday at Age 50 2036-04-01 04:00:00 TUESDAY
Birthday at Age 60 2046-04-01 05:00:00 SUNDAY
Birthday at Age 70 2056-04-01 05:00:00 SATURDAY
Birthday at Age 80 2066-04-01 04:00:00 THURSDAY
Birthday at Age 90 2076-04-01 04:00:00 WEDNESDAY
Birthday at Age 100 2086-04-01 04:00:00 MONDAYPredefined Libraries
~/bin/codemd ../Prj/datetime/bday/src/bday.adb -x Environment -l0006 | with Ada.Calendar; use Ada.Calendar;
0007 | with Ada.Calendar.Formatting;
0008 | with Ada.Calendar.Arithmetic; use Ada.Calendar.Arithmetic;Date of Birth Computations
~/bin/codemd ../Prj/datetime/bday/src/bday.adb -x Calc -l0022 | procedure Show_Birthday (dob : Ada.Calendar.Time; age : Positive) is
0023 | reqbday : Ada.Calendar.Time;
0024 | begin
0025 | reqbday := Time_Of (Year (dob) + age, Month (dob), Day (dob));
0026 |
0027 | Put ("Birthday at Age ");
0028 | Put (Positive'Image (age));
0029 | Set_Col (24);
0030 | Put (Formatting.Image (reqbday));
0031 | Set_Col (44);
0032 | Put (Formatting.Day_Of_Week (reqbday)'Image);
0033 | New_Line;
0034 | end Show_Birthday;Date Comparison
Passage of Time
Given 2 dates, determine which is older. Essentially date comparisons.
Assuming these are dates of birth, determine the year when the older age will be double the younger. Triple the younger.
~/bin/dates 1996-10-07dates
dates.P1
Person A
Birthday 1986-04-01 06:00:01
Day of the Week TUESDAY
Age today 14191 days
38 years
Person B
Birthday 1996-10-07 06:00:01
Day of the Week MONDAY
Age today 10349 days
28 years
Person A is older
Age difference is 3842 days
or 10 years
Double the Age
On 2006-10-07 04:00:00
Person B
will be 10 years old
Person A
will be 20 years oldGiven 2 dates of birth determine who is older. Then project when the older person will be double the age of the younger person.
~/bin/codemd ../Prj/datetime/bday/src/dates.adb -x Compare -l0066 | procedure AgeDiff (operson : String; od : Time; yperson : String; yd : Time)
0067 | is
0068 | agediff : Day_Count;
0069 | yearsdiff : Integer;
0070 | dblage : Time := od;
0071 | begin
0072 | Put ("Person ");
0073 | Put (operson);
0074 | Put_Line (" is older");
0075 | agediff := yd - od;
0076 | yearsdiff := Integer (agediff / days_in_year);
0077 | Put ("Age difference is ");
0078 | Put (agediff'Image);
0079 | Put_Line (" days");
0080 | Put (" or ");
0081 | Put (yearsdiff'Image);
0082 | Put_Line (" years");
0083 | Put_Line ("Double the Age");
0084 | dblage := Age (yd, yearsdiff);
0085 |
0086 | Put ("On ");
0087 | Put_Line (Formatting.Image (dblage));
0088 | Show_Age (yperson, yd, dblage);
0089 | Show_Age (operson, od, dblage);
0090 | end AgeDiff;Add a number of years to a date of birth.
~/bin/codemd ../Prj/datetime/bday/src/dates.adb -x AddYears -l0056 | function Age (dob : Time; years : Integer) return Time is
0057 | agedTime : Time := dob;
0058 | begin
0059 | agedTime :=
0060 | Time_Of (Year_Number (Year (dob) + years), Month (dob), Day (dob));
0061 | return agedTime;
0062 | end Age;Sleep or delay execution for a specified length of time
Set an alarm to wake up at a specific time
Creating a widget to help identify performance sensitive sections of code
Sleep for a specified length of time
~/bin/realtime p1realtime
realtime.P1
Sleeping for 3.000000000 seconds
Woke up
Slept from 2025-02-06 10:36:11 to 2025-02-06 10:36:14Sleep till a specified time or set an alarm
~/bin/realtime p2realtime
realtime.P2
Sleeping till 2025-02-06 10:36:23 seconds
Woke up
Slept from 2025-02-06 10:36:14 to 2025-02-06 10:36:23Perform computations and measure the time it takes for different count of cycles.
~/bin/codemd ../Prj/datetime/bday/src/realtime.adb -x Time -l0079 | Put ("Starting computations ");
0080 | Put (iterations'Image);
0081 | Put (" cycles");
0082 | t1 := Clock;
0083 |
0084 | for i in 1 .. iterations loop
0085 | result := Cosh (Float (i) * vf) + Sinh (Float (i) * vf);
0086 | end loop;
0087 | t2 := Clock;
0088 | Put ("Completed ");
0089 | Put (Duration'Image (t2 - t1));
0090 | Put_Line (" seconds");~/bin/realtime p3 10000
~/bin/realtime p3 20000realtime
realtime.P3
Starting computations 10240000 cyclesCompleted 0.058872000 seconds
realtime
realtime.P3
Starting computations 20480000 cyclesCompleted 0.108147000 secondsRepository: TechAdaBook
Directory: Prj/datetime