如何遍历定界字符串并将字符串内容分配给本地delphi变量？

Question

I have written a Delphi function that loads data from a .dat file into a string list. It then decodes the string list and assigns to a string variable. The contents of the string use the '#' symbol as a separator.

How can I then take the contents of this string and then assign its contents to local variables?

// Function loads data from a dat file and assigns to a String List.
function TfrmMain.LoadFromFile;
var 
  index, Count : integer;
  profileFile, DecodedString : string;
begin
  // Open a file and assign to a local variable.
  OpenDialog1.Execute;
  profileFile := OpenDialog1.FileName;
  if profileFile = '' then
    exit;
  profileList := TStringList.Create;
  profileList.LoadFromFile(profileFile);
  for index := 0 to profileList.Count - 1 do
  begin
    Line := '';
    Line := profileList[Index];
  end;
end;

After its been decoded the var "Line" contains something that looks like this:

example:

Line '23#80#10#2#1#...255#'.

Not all of the values between the separators are the same length and the value of "Line" will vary each time the function LoadFromFile is called (eg sometimes a value may have only one number the next two or three etc so I cannot rely on the Copy function for strings or arrays).

I'm trying to figure out a way of looping through the contents of "Line", assigning it to a local variable called "buffer" and then if it encounters a '#' it then assigns the value of buffer to a local variable, re-initialises buffer to ''; and then moves onto the next value in "Line" repeating the process for the next parameter ignoring the '#' each time.

I think I have been scratching around with this problem for too long now and I cannot seem to make any progress and need a break from it. If anyone would care to have a look, I would welcome any suggestions on how this might be achieved.

Many Thanks

KD

Answer 1

You need a second TStringList:

  lineLst := TStringList.Create;
  try
    lineLst.Delimiter := '#';
    lineLst.DelimitedText := Line;
    ...
  finally
    lineLst.Free;
  end;

Depending on your Delphi version you can set lineLst.StrictDelimiter := true in case the line contains spaces.

Answer 2

You can do something like this:

program Project1;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  System.SysUtils, StrUtils;

var
  S : string;
  D : string;

begin
  S := '23#80#10#2#1#...255#';

  for D in SplitString(S,'#') do //SplitString is in the StrUtils unit
    writeln(D);

  readln;
end.

Answer 3

You did not tag your Delphi version, so i don't know if it applies or not. That IS version-specific. Please do!

In order of my personal preference:

1: Download Jedi CodeLib - http://jcl.sf.net . Then use TJclStringList. It has very nice split method. After that you would only have to iterate through.

function Split(const AText, ASeparator: string; AClearBeforeAdd: Boolean = True): IJclStringList;

uses JclStringLists;
...
var s: string;  js: IJclStringList.
begin
...
   js := TJclStringList.Create().Split(input, '#', True);
   for s in js do begin
      .....
   end;
...
end;

2: Delphi now has somewhat less featured StringSplit routine. http://docwiki.embarcadero.com/Libraries/en/System.StrUtils.SplitString It has a misfeature that array of string type may be not assignment-compatible to itself. Hello, 1949 Pascal rules...

uses StrUtils;
...
var s: string;  
    a_s: TStringDynArray; 
(* aka array-of-string aka TArray<string>. But you have to remember this term exactly*)
begin
...
   a_s := SplitString(input, '#');
   for s in a_s do begin
      .....
   end;
...
end;

3: Use TStringList. The main problem with it is that it was designed that spaces or new lines are built-in separators. In newer Delphi that can be suppressed. Overall the code should be tailored to your exact Delphi version. You can easily Google for something like "Using TStringlist for splitting string" and get a load of examples (like @Uwe's one).

But you may forget to suppress here or there. And you may be on old Delphi,, where that can not be done. And you may mis-apply example for different Delphi version. And... it is just boring :-) Though you can make your own function to generate such pre-tuned stringlists for you and carefully check Delphi version in it :-) But then You would have to carefully free that object after use.

Answer 4

I use a function I've written called Fetch . I think I stole the idea from the Indy library some time ago:

function Fetch(var VString: string; ASeperator: string = ','): string;
var   LPos: integer;
begin
  LPos := AnsiPos(ASeperator, VString);
  if LPos > 0 then
  begin
    result := Trim(Copy(VString, 1, LPos - 1));
    VString := Copy(VString, LPos + 1, MAXINT);
  end
  else
  begin
    result := VString;
    VString := '';
  end;
end;

Then I'd call it like this:

var
  value: string;
  line: string;
  profileFile: string;
  profileList: TStringList;
  index: integer;
begin
  if OpenDialog1.Execute then
  begin 
    profileFile := OpenDialog1.FileName;
    if (profileFile = '') or not FileExists(profileFile) then
      exit;

    profileList := TStringList.Create;
    try
      profileList.LoadFromFile(profileFile);

      for index := 0 to profileList.Count - 1 do
      begin
        line := profileList[index];
        Fetch(line, ''''); //discard "Line '"
        value := Fetch(line, '#')
        while (value <> '') and (value[1] <> '''') do //bail when we get to the quote at the end
        begin
           ProcessTheNumber(value); //do whatever you need to do with the number
           value := Fetch(line, '#');
        end;
      end;
    finally
      profileList.Free;
    end;
  end;
end;

Note: this was typed into the browser, so I haven't checked it works.