When extracting data from text or other operating systems the format of date strings can vary dramatically. Borland function StrToDateTime() converts a string to a TDateTime value, but it is limited to the fact that the string parameter must be in the format of the current locale's date/time format. eg. "MM/DD/YY HH:MM:SS"

 

Answer:

This is of little use when extracting dates such as ..

 

 

This function will evaluate a DateTime string in accordance to the DateTime specifier format string supplied. The following specifiers are supported ...

 

 

NOTE : One assumption I have to make is that DAYS, MONTHS, HOURS and MINUTES have a leading ZERO or SPACE (ie. are 2 chars long) and MILLISECONDS are 3 chars long (ZERO or SPACE padded)

 

Using function

Code:

DateTimeStrEval(const DateTimeFormat : string; const DateTimeStr : string) : TDateTime;

 

The above Examples (1..4) can be evaluated as ... (Assume DT1 to DT4 equals example strings 1..4)

 

Code:

MyDate := DateTimeStrEval('dddd dd mmmm yyyy hh:nnampm (ss xxxx)', DT1);        MyDate := DateTimeStrEval('yyyymmdd', DT2);        MyDate := DateTimeStrEval('dd-mmm-yy', DT3);        MyDate := DateTimeStrEval('hh xxxx nn xxxxxx ss xxxxxx zzz xxxxx', DT4);

 

Code:

uses SysUtils, DateUtils   // ============================================================================= // Evaluate a date time string into a TDateTime obeying the // rules of the specified DateTimeFormat string // eg. DateTimeStrEval('dd-MMM-yyyy hh:nn','23-May-2002 12:34) // // Delphi 6 Specific in DateUtils can be translated to .... // // YearOf() // // function YearOf(const AValue: TDateTime): Word; // var LMonth, LDay : word; // begin //   DecodeDate(AValue,Result,LMonth,LDay); // end; // // TryEncodeDateTime() // // function TryEncodeDateTime(const AYear,AMonth,ADay,AHour,AMinute,ASecond, //                            AMilliSecond : word; //                            out AValue : TDateTime): Boolean; // var LTime : TDateTime; // begin //   Result := TryEncodeDate(AYear, AMonth, ADay, AValue); //   if Result then begin //     Result := TryEncodeTime(AHour, AMinute, ASecond, AMilliSecond, LTime); //     if Result then //        AValue := AValue + LTime; //   end; // end; // // (TryEncodeDate() and TryEncodeTime() is the same as EncodeDate() and //  EncodeTime() with error checking and boolean return value) // // =============================================================================   function DateTimeStrEval(const DateTimeFormat: string; const DateTimeStr: string): TDateTime; var i, ii, iii: integer; Retvar: TDateTime; Tmp,    Fmt, Data, Mask, Spec: string; Year, Month, Day, Hour,    Minute, Second, MSec: word; AmPm: integer; begin Year := 1; Month := 1; Day := 1; Hour := 0; Minute := 0; Second := 0; MSec := 0; Fmt := UpperCase(DateTimeFormat); Data := UpperCase(DateTimeStr); i := 1; Mask := ''; AmPm := 0;   while i < length(Fmt) do begin    if Fmt[i] in ['A', 'P', 'D', 'M', 'Y', 'H', 'N', 'S', 'Z'] then    begin      // Start of a date specifier      Mask := Fmt[i];      ii := i + 1;        // Keep going till not valid specifier      while true do      begin        if ii > length(Fmt) then          Break; // End of specifier string        Spec := Mask + Fmt[ii];          if (Spec = 'DD') or (Spec = 'DDD') or (Spec = 'DDDD') or          (Spec = 'MM') or (Spec = 'MMM') or (Spec = 'MMMM') or          (Spec = 'YY') or (Spec = 'YYY') or (Spec = 'YYYY') or          (Spec = 'HH') or (Spec = 'NN') or (Spec = 'SS') or          (Spec = 'ZZ') or (Spec = 'ZZZ') or          (Spec = 'AP') or (Spec = 'AM') or (Spec = 'AMP') or          (Spec = 'AMPM') then        begin          Mask := Spec;          inc(ii);        end        else        begin          // End of or Invalid specifier          Break;        end;      end;        // Got a valid specifier ? - evaluate it from data string      if (Mask <> '') and (length(Data) > 0) then      begin        // Day 1..31        if (Mask = 'DD') then        begin          Day := StrToIntDef(trim(copy(Data, 1, 2)), 0);          delete(Data, 1, 2);        end;          // Day Sun..Sat (Just remove from data string)        if Mask = 'DDD' then          delete(Data, 1, 3);          // Day Sunday..Saturday (Just remove from data string LEN)        if Mask = 'DDDD' then        begin          Tmp := copy(Data, 1, 3);          for iii := 1 to 7 do          begin            if Tmp = Uppercase(copy(LongDayNames[iii], 1, 3)) then            begin              delete(Data, 1, length(LongDayNames[iii]));              Break;            end;          end;        end;          // Month 1..12        if (Mask = 'MM') then        begin          Month := StrToIntDef(trim(copy(Data, 1, 2)), 0);          delete(Data, 1, 2);        end;          // Month Jan..Dec        if Mask = 'MMM' then        begin          Tmp := copy(Data, 1, 3);          for iii := 1 to 12 do          begin            if Tmp = Uppercase(copy(LongMonthNames[iii], 1, 3)) then            begin              Month := iii;              delete(Data, 1, 3);              Break;            end;          end;        end;          // Month January..December        if Mask = 'MMMM' then        begin          Tmp := copy(Data, 1, 3);          for iii := 1 to 12 do          begin            if Tmp = Uppercase(copy(LongMonthNames[iii], 1, 3)) then            begin              Month := iii;              delete(Data, 1, length(LongMonthNames[iii]));              Break;            end;          end;        end;          // Year 2 Digit        if Mask = 'YY' then        begin          Year := StrToIntDef(copy(Data, 1, 2), 0);          delete(Data, 1, 2);          if Year < TwoDigitYearCenturyWindow then            Year := (YearOf(Date) div 100) * 100 + Year          else            Year := (YearOf(Date) div 100 - 1) * 100 + Year;        end;          // Year 4 Digit        if Mask = 'YYYY' then        begin          Year := StrToIntDef(copy(Data, 1, 4), 0);          delete(Data, 1, 4);        end;          // Hours        if Mask = 'HH' then        begin          Hour := StrToIntDef(trim(copy(Data, 1, 2)), 0);          delete(Data, 1, 2);        end;          // Minutes        if Mask = 'NN' then        begin          Minute := StrToIntDef(trim(copy(Data, 1, 2)), 0);          delete(Data, 1, 2);        end;          // Seconds        if Mask = 'SS' then        begin          Second := StrToIntDef(trim(copy(Data, 1, 2)), 0);          delete(Data, 1, 2);        end;          // Milliseconds        if (Mask = 'ZZ') or (Mask = 'ZZZ') then        begin          MSec := StrToIntDef(trim(copy(Data, 1, 3)), 0);          delete(Data, 1, 3);        end;          // AmPm A or P flag        if (Mask = 'AP') then        begin          if Data[1] = 'A' then            AmPm := -1          else            AmPm := 1;          delete(Data, 1, 1);        end;          // AmPm AM or PM flag        if (Mask = 'AM') or (Mask = 'AMP') or (Mask = 'AMPM') then        begin          if copy(Data, 1, 2) = 'AM' then            AmPm := -1          else            AmPm := 1;          delete(Data, 1, 2);        end;          Mask := '';        i := ii;      end;    end    else    begin      // Remove delimiter from data string      if length(Data) > 1 then        delete(Data, 1, 1);      inc(i);    end; end;   if AmPm = 1 then    Hour := Hour + 12; if not TryEncodeDateTime(Year, Month, Day, Hour, Minute, Second, MSec, Retvar) then    Retvar := 0.0; Result := Retvar; end;