Run-length encoding: Difference between revisions

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 %2 = "WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW"</pre>
+=={{header|Pascal}}==
+<lang pascal>Program RunLengthEncoding(output);
+procedure encode(s: string; var counts: array of integer; var letters: string);
+  var
+    i, j: integer;
+  begin
+    j := 0;
+    letters := '';
+    if length(s) > 0 then
+    begin
+      j := 1;
+      letters := letters + s[1];
+      counts[1] := 1;
+      for i := 2 to length(s) do
+        if s[i] = letters[j] then
+          inc(counts[j])
+        else
+        begin
+          inc(j);
+          letters := letters + s[i];
+          counts[j] := 1;
+        end;
+    end;
+  end;
+procedure decode(var s: string; counts: array of integer; letters: string);
+  var
+    i, j: integer;
+  begin
+    s := '';
+    for i := 1 to length(letters) do
+      for j := 1 to counts[i] do
+        s := s + letters[i];
+  end;
+var
+  s: string;
+  counts: array of integer;
+  letters: string;
+  i: integer;
+begin
+  s := 'WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWW';
+  writeln(s);
+  setlength(counts, length(s));
+  encode(s, counts, letters);
+  for i := 1 to length(letters) - 1 do
+    write(counts[i], ' * ', letters[i], ', ');
+  writeln(counts[length(letters)], ' * ', letters[length(letters)]);
+  decode(s, counts, letters);
+  writeln(s);
+end.</lang>
+Output:
+<pre>:> ./RunLengthEncoding
+WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWW
+* W, 1 * B, 12 * W, 3 * B, 24 * W, 1 * B, 13 * W
+WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWW
+</pre>
 =={{header|Perl}}==