Delphi provides a straight forward function can replace string - StringReplace
Below code shows an example
unit Unit1; interface uses SysUtils, // Unit containing the stringreplace command Forms, Dialogs; type TForm1 = class(TForm) procedure FormCreate(Sender: TObject); end; var Form1: TForm1; implementation {$R *.dfm} // Include form definitions procedure TForm1.FormCreate(Sender: TObject); var before, after : string; begin // Try to replace all occurrences of a or A to THE before := 'This is a way to live A big life'; after := stringreplace(before, ' a ', ' THE ', [rfReplaceAll, rfIgnoreCase]); ShowMessage('Before = '+before); ShowMessage('After = '+after); end;