How can I separate the server name from the port number in a string?

If there is a mail server string like smtp.gmail.com:587, how could I parse it开发者_运维知识库 to save "smtp.gmail.com" in a string variable and "587" in another?

function SplitAtChar(const Str: string; const Chr: char;
  out Part1, Part2: string): boolean;
var
  ChrPos: integer;
begin
  result := true;
  ChrPos := Pos(Chr, Str);
  if ChrPos = 0 then
    Exit(false);
  Part1 := Copy(Str, 1, ChrPos - 1);
  Part2 := Copy(Str, ChrPos + 1, MaxInt);
end;

Sample usage:

var
  p1, p2: string;
begin
  if SplitAtChar('smtp.gmail.com:587', ':', p1, p2) then
  begin
    ShowMessage(p1);
    ShowMessage(p2);
  end;

If you are using Delphi XE and want a one-liner instead of bothering with regex:

uses
  Types, StrUtils;
var
  StrArr: TStringDynArray;
begin
  StrArr := SplitString('smtp.gmail.com:587', ':');
  Assert(StrArr[0] = 'smtp.gmail.com');
  Assert(StrArr[1] = '587');
end.

If you're using Delphi XE, you might also use the built-in regular expression support:

uses RegularExpressions;

procedure parse(const pInput: string; var vHostname,
  vPortNumber: string);
var
  l_Regex: TRegEx;
  l_Match: TMatch;
begin
  l_Regex := TRegEx.Create('^([a-zA-Z0-9.]+)(:([0-9]+))?$');
  l_Match := l_RegEx.Match(pInput);
  if l_Match.Success then
  begin
    vHostname := l_Match.Groups[1].Value;
    if l_Match.Groups.Count > 3 then
      vPortNumber := l_Match.Groups[3].Value
    else
      vPortNumber := '25'; // default SMTP port
  end
  else
    begin
    vHostname := '';
    vPortNumber := '';
  end;
end;

This will match smtp.gmail.com:587, as well as smtp.gmail.com (in the latter case, vPortNumber is assigned the standard SMTP port 25).

The Indy TIdURI class can split any URI into its parts (protocol, host, port, user, password, path, etc). Indy is included in Delphi. TIdURI bas some bugs reported here and mentioned here, planned to be fixed in Indy 11.