Ada (programming language): Difference between revisions

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Types can have modifiers such as ''limited, abstract, private'' etc. Private types do not show their inner structure; objects of limited types cannot be copied.<ref>{{cite web |title=Ada Syntax Card |url=http://www.digilife.be/quickreferences/QRC/Ada%20Syntax%20Card.pdf |access-date=28 February 2011 |url-status=dead |archive-url=https://web.archive.org/web/20110706133825/http://www.digilife.be/quickreferences/QRC/Ada%20Syntax%20Card.pdf |archive-date=6 July 2011}}</ref> Ada 95 adds further features for object-oriented extension of types.

=== Control structures ===

Ada is a [[structured programming]] language, meaning that the flow of control is structured into standard statements. All standard constructs and deep-level early exit are supported, so the use of the also supported "[[goto (command)|go to]]" commands is seldom needed.

<syntaxhighlight lang="ada" line>

-- while a is not equal to b, loop.

while a /= b loop

Ada.Text_IO.Put_Line ("Waiting");

end loop;

if a > b then

Ada.Text_IO.Put_Line ("Condition met");

else

Ada.Text_IO.Put_Line ("Condition not met");

end if;

for i in 1 .. 10 loop

Ada.Text_IO.Put ("Iteration: ");

Ada.Text_IO.Put (i);

Ada.Text_IO.Put_Line;

end loop;

loop

a := a + 1;

exit when a = 10;

end loop;

case i is

when 0 => Ada.Text_IO.Put ("zero");

when 1 => Ada.Text_IO.Put ("one");

when 2 => Ada.Text_IO.Put ("two");

-- case statements have to cover all possible cases:

when others => Ada.Text_IO.Put ("none of the above");

end case;

for aWeekday in Weekday'Range loop -- loop over an enumeration

Put_Line ( Weekday'Image(aWeekday) ); -- output string representation of an enumeration

if aWeekday in Working_Day then -- check of a subtype of an enumeration

Put_Line ( " to work for " &

Working_Hours'Image (Work_Load(aWeekday)) ); -- access into a lookup table

end if;