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Ada: Container, Dateien und Zeit

Properties1
tagsprogrammiersprachen, ada

4 Min. Lesezeit

Kurz: Die Standardbibliothek Ada.Containers bietet generische Datenstrukturen:

Teil des Kurses Ada

Kapitel 6 von 8 im Kurs Ada. Mit Fortschritt, Quiz und Zertifikat auf der Lernseite.

Vektoren, Maps und Sets

Die Standardbibliothek Ada.Containers bietet generische Datenstrukturen:

with Ada.Text_IO; use Ada.Text_IO;
with Ada.Containers.Vectors;
with Ada.Containers.Indefinite_Ordered_Maps;
with Ada.Containers.Ordered_Sets;
 
procedure Main is
   package Int_Vektor is new Ada.Containers.Vectors (Index_Type => Positive, Element_Type => Integer);
   package Alter_Map is new Ada.Containers.Indefinite_Ordered_Maps (String, Natural);
   package Int_Set is new Ada.Containers.Ordered_Sets (Integer);
   package Sortierer is new Int_Vektor.Generic_Sorting;
   use Int_Vektor;
 
   V : Vector;
   M : Alter_Map.Map;
   S : Int_Set.Set;
   Summe : Integer := 0;
begin
   V.Append (5); V.Append (3); V.Append (9);
   V.Prepend (1);
   Put_Line (Ada.Containers.Count_Type'Image (V.Length) & Integer'Image (V.First_Element) & Integer'Image (V.Last_Element));
   for X of V loop
      Summe := Summe + X;
   end loop;
   Put_Line (Integer'Image (Summe));
   Sortierer.Sort (V);
   for X of V loop Put (Integer'Image (X)); end loop;
   New_Line;
 
   M.Insert ("Mia", 17);
   M.Insert ("Tom", 25);
   M.Include ("Mia", 18);
   for C in M.Iterate loop
      Put_Line (Alter_Map.Key (C) & " =" & Natural'Image (Alter_Map.Element (C)));
   end loop;
   Put_Line (Boolean'Image (M.Contains ("Tom")) & Boolean'Image (M.Contains ("Zoe")));
 
   S.Insert (3); S.Insert (1); S.Include (3); S.Insert (2);
   Put_Line (Ada.Containers.Count_Type'Image (S.Length));
   for X of S loop Put (Integer'Image (X)); end loop;
   New_Line;
end Main;

Ausgabe:

4 1 9
 18
 1 3 5 9
Mia = 18
Tom = 25
TRUEFALSE
 3
 1 2 3

Textdateien

with Ada.Text_IO; use Ada.Text_IO;
 
procedure Main is
   F : File_Type;
   Pfad : constant String := "ada-demo.txt";
   Zeilen : Natural := 0;
begin
   Create (F, Out_File, Pfad);
   Put_Line (F, "eins");
   Put_Line (F, "zwei");
   Put_Line (F, "drei");
   Close (F);
 
   Open (F, In_File, Pfad);
   while not End_Of_File (F) loop
      declare
         Zeile : constant String := Get_Line (F);
      begin
         Zeilen := Zeilen + 1;
         Put_Line (Natural'Image (Zeilen) & ": " & Zeile);
      end;
   end loop;
   Close (F);
 
   Open (F, Append_File, Pfad);
   Put_Line (F, "vier");
   Close (F);
 
   Open (F, In_File, Pfad);
   Zeilen := 0;
   while not End_Of_File (F) loop
      declare
         Dummy : constant String := Get_Line (F);
      begin
         Zeilen := Zeilen + 1;
      end;
   end loop;
   Close (F);
   Put_Line (Natural'Image (Zeilen));
 
   Open (F, In_File, Pfad);
   Delete (F);
exception
   when Name_Error => Put_Line ("Datei nicht gefunden");
end Main;

Ausgabe:

1: eins
 2: zwei
 3: drei
 4

Zeit und Kalender

with Ada.Text_IO; use Ada.Text_IO;
with Ada.Calendar; use Ada.Calendar;
with Ada.Calendar.Formatting;
with Ada.Calendar.Arithmetic;
 
procedure Main is
   T : constant Time := Time_Of (2024, 3, 15, 14 * 3600.0 + 30 * 60.0);
   Spaeter : constant Time := T + Duration (86_400);
   Tage : Ada.Calendar.Arithmetic.Day_Count;
   Sekunden : Duration;
   Schalt : Ada.Calendar.Arithmetic.Leap_Seconds_Count;
begin
   Put_Line (Integer'Image (Year (T)) & Integer'Image (Month (T)) & Integer'Image (Day (T)));
   Put_Line (Ada.Calendar.Formatting.Image (T));
   Put_Line (Ada.Calendar.Formatting.Image (Spaeter, Include_Time_Fraction => False));
   Ada.Calendar.Arithmetic.Difference (Spaeter, T, Tage, Sekunden, Schalt);
   Put_Line (Integer'Image (Integer (Tage)) & " Tag(e)");
   Put_Line (Ada.Calendar.Formatting.Day_Of_Week (T)'Image);
   delay 0.05;
   Put_Line ("Wartezeit vorbei");
end Main;

Ausgabe:

2024 3 15
2024-03-15 14:30:00
2024-03-16 14:30:00
 1 Tag(e)
FRIDAY
Wartezeit vorbei

Umgebung und Zufall

with Ada.Text_IO; use Ada.Text_IO;
with Ada.Command_Line;
with Ada.Environment_Variables;
with Ada.Numerics.Discrete_Random;
with Ada.Numerics.Elementary_Functions; use Ada.Numerics.Elementary_Functions;
 
procedure Main is
   subtype Wuerfel is Integer range 1 .. 6;
   package Zufall is new Ada.Numerics.Discrete_Random (Wuerfel);
   G : Zufall.Generator;
   Wurf : Wuerfel;
begin
   Put_Line (Integer'Image (Ada.Command_Line.Argument_Count));
   Put_Line (Boolean'Image (Ada.Environment_Variables.Exists ("PATH")));
   Zufall.Reset (G, 42);
   Wurf := Zufall.Random (G);
   Put_Line (Boolean'Image (Wurf in 1 .. 6));
   Put_Line (Float'Image (Sqrt (16.0)));
   Put_Line (Float'Image (Float'Floor (2.7)));
   Put_Line (Float'Image (Float'Rounding (2.5)));
   Put_Line (Float'Image (Log (100.0, 10.0)));
end Main;

Ausgabe:

0
TRUE
TRUE
 4.00000E+00
 2.00000E+00
 3.00000E+00
 2.00000E+00

Merke

  • Ada.Containers liefert Vectors, Maps, Sets und mehr als generische Pakete
  • Dateien: Create, Open, Get_Line, Put_Line, Close, End_Of_File
  • Ada.Calendar und Ada.Calendar.Formatting rechnen mit Datum und Zeit
  • Ada.Numerics.* bietet Zufall und Mathematikfunktionen

Übungsaufgabe

Lies Zahlen aus einer Datei in einen Vektor ein und sortiere sie.

Quiz zur Selbstkontrolle

Weiter im Kurs

Zurück: Tasks, geschützte Objekte und Verträge

Weiter: Praxisbeispiele

Alle Kapitel: Ada im Überblick

Graphansicht

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