Selectively replace multiple instances of a character within a string: Difference between revisions
Selectively replace multiple instances of a character within a string (view source)
Revision as of 12:55, 20 June 2024
, 9 days agoAdded Ada version
m (→{{header|Wren}}: Changed to Wren S/H) |
(Added Ada version) |
||
Line 40:
<pre>
abracadabra -> AErBcadCbFD
</pre>
=={{header|Ada}}==
<syntaxhighlight lang="ada">
-- Selectively replace multiple instances of a character within a string
-- J. Carter 2024 Jun
with Ada.Strings.Fixed;
with Ada.Text_IO;
procedure Selectively_Replace is
procedure Replace
(Letter : in Character; Occurrence : in Positive; Within : in String; By : in Character; Into : in out String)
with Pre => Into'First = Within'First and Into'Last = Within'Last;
-- Finds the index of the Occurrence-th instance of Letter in Within and sets the character in Into at that index to By
-- If there is no such index, has no effect
-- Before the first call to replace, Within should be = Into
procedure Replace
(Letter : in Character; Occurrence : in Positive; Within : in String; By : in Character; Into : in out String)
is
Start : Natural := 0;
begin -- Replace
Find : for I in 1 .. Occurrence loop
Start := Ada.Strings.Fixed.Index (Within, Letter & "", Start + 1);
if Start = 0 then -- Within has fewer than Occurrence instances of Letter
return;
end if;
end loop Find;
Into (Start) := By;
end Replace;
Source : constant String := "abracadabra";
Result : String := Source;
begin -- Selectively_Replace
Replace (Letter => 'a', Occurrence => 1, Within => Source, By => 'A', Into => Result);
Replace (Letter => 'a', Occurrence => 2, Within => Source, By => 'B', Into => Result);
Replace (Letter => 'a', Occurrence => 4, Within => Source, By => 'C', Into => Result);
Replace (Letter => 'a', Occurrence => 5, Within => Source, By => 'D', Into => Result);
Replace (Letter => 'b', Occurrence => 1, Within => Source, By => 'E', Into => Result);
Replace (Letter => 'r', Occurrence => 2, Within => Source, By => 'F', Into => Result);
Ada.Text_IO.Put_Line (Item => Source & " => " & Result);
end Selectively_Replace;
</syntaxhighlight>
{{out}}
<pre>
abracadabra => AErBcadCbFD
</pre>
| |||