Add function_procedure example

simple_examples/function_procedure.pas

@@ -0,0 +1,22 @@
+program function_procedure;
+
+{$mode objfpc}{$H+}
+
+uses strutils;
+
+procedure DisplayMessage(const aMsg: string);
+begin
+	WriteLn(DupeString('-', Length(aMsg)));
+	WriteLn(aMsg);
+	WriteLn(DupeString('=', Length(aMsg)));
+end;
+
+const LazDescription = 'Lazarus is a very powerful IDE';
+begin
+	DisplayMessage(LazDescription);
+	DisplayMessage('The message above will now be shown backwards.');
+	DisplayMessage(ReverseString(LazDescription));
+	{$IFDEF WINDOWS}
+	ReadLn;
+	{$ENDIF}
+end.