Mirror

How to parse a line from a comma-separated file into a record (Views: 100)


Problem/Question/Abstract:

How to parse a line from a comma-separated file into a record

Answer:

{ ... }
type
  TRec = record
    lastname, firstname: string[30];
    age: Integer;
    position: string[40];
    salary: Single;
  end;

procedure ParseLine(const Line: string; var rec: TRec);
var
  i, start, field: Integer;

  procedure CopyField(currPos: Integer);
  var
    len, err: Integer;
    temp: string;
  begin
    len := currpos - start;
    if len > 0 then
    begin
      temp := Copy(Line, start, len);
      err := 0;
      with rec do
        case field of
          0: lastname := temp;
          1: firstname := temp;
          2: Val(temp, age, err);
          3: position := temp;
          4: Val(temp, salary, err)
        else
          { too much data in this line, issue error message }
        end;
      if err <> 0 then
      begin
        {issue error message}
      end;
    end
    else
      {no data in this field, issue error message or leave the default }
  end;

begin
  {set defaults for the fields, init variables}
  FillChar(rec, sizeof(rec), 0);
  field := 0; {fields keeps track of which field to fill next}
  start := 1; {fencepost for start of field data}
  for i := 1 to Succ(Length(Line)) do
  begin
    if i > Length(Line) then
    begin
      {copy the last section of the line to the last field}
      CopyField(i);
    end
    else
      {test for separator character} if Line[i] = ',' then
      begin
        {found one, copy data from current fencepost to this separator}
        CopyField(i);
        {advance fencepost to position after separator}
        start := i + 1;
        {next field}
        Inc(field);
      end;
  end;
end;

<< Back to main page