System.Pos Function

Returns the index value of the first character in a specified substring that occurs in a given string.

Pascal

function Pos(const substr: UnicodeString; const str: UnicodeString): Integer; overload;
function Pos(const substr: RawByteString; const str: RawByteString): Integer; overload;
function Pos(const substr: WideString; const str: WideString): Integer; overload;

C++

int Pos(const UnicodeString substr, const UnicodeString str);
int Pos(const RawByteString substr, const RawByteString str);
int Pos(const BSTR substr, const BSTR str);

File

System

Description

In Delphi, Pos searches for a substring, Substr, in a string, S. Substr and S are string-type expressions.

Pos searches for Substr within S and returns an integer value that is the index of the first character of Substr within S. Pos is case-sensitive. If Substr is not found, Pos returns zero.

The PosEx function is similar to Pos, but provides additional features and can be used in C++ code.

Delphi Examples:

Copy Code

{
The following example updates the strings in a list box
given the strings contained in another list box. If a string
in the source list box has the form Name=Value and the
destination list box contains a string with the same Name
part, the Value part in the destination list box will be
replaced by the source’s value.  TListBox objects that are
not name-value pairs are not assigned a Name and IndexOfName
will return -1.
}
procedure MergeStrings(Dest, Source: TStrings);
var
  I, DI: Integer;
  begin
  for I := 0 to Source.Count - 1 do
  begin
    if Pos ('=', Source[I]) > 1 then
    begin
      DI := Dest.IndexOfName(Source.Names[I]);
      if DI > -1 then Dest[DI] := Source[I];
    end;
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  MergeStrings(ListBox1.Items, ListBox2.Items);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  ListBox1.Items.Add('Plants = 10');
  ListBox1.Items.Add('Animals = 20');
  ListBox1.Items.Add('Minerals = 15');
  ListBox2.Items.Add('Animals = 4');
  ListBox2.Items.Add('Plants = 3');
  ListBox2.Items.Add('Minerals = 78');
end;

Copy Code

{
This example demonstrates how to edit particular elements of a string.
}
procedure TForm1.Button1Click(Sender: TObject);
var S: string;
begin
  S := Edit1.Text;
  { Convert spaces to zeros }
  while Pos(' ', S) > 0 do
    S[Pos(' ', S)] := '0';
  Edit1.Text := S;
end;