Как преобразовать строку в дату?
Как преобразовать строку в дату?
Функция StrToDate преобразует только числа, поэтому, если у Вас месяцы в виде имён, то прийдётся использовать VarToDateTime.
var
D1, D2, D3 : TDateTime;
begin
D1 := VarToDateTime('December 6, 1969');
D2 := VarToDateTime('6-Apr-1998');
D3 := VarToDateTime('1998-Apr-6');
ShowMessage(DateToStr(D1)+' '+DateToStr(D2)+' '+
DateToStr(D3));
end;
Взято с Исходников.ru
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 .. 1) "Friday 18 October 2002 08:34am (45 secs)" or "Wednesday 15 May 2002 06:12 (22 secs)"
2) "20020431"
3) "12.Nov.03"
4) "14 Hour 31 Minute 25 Second 321 MSecs"
This function will evaluate a DateTime string in accordance to the DateTime specifier format string supplied. The following specifiers are supported ...
dd the day as a number with a leading zero or space (01-31).
ddd the day as an abbreviation (Sun-Sat)
dddd the day as a full name (Sunday-Saturday)
mm
the month as a number with a leading zero or space (01-12).
mmm
the month as an abbreviation (Jan-Dec)
mmmm the month as a full name (January-December)
yy
the year as a two-digit number (00-99).
yyyy
the year as a four-digit number (0000-9999).
hh
the hour with a leading zero or space (00-23)
nn
the minute with a leading zero or space (00-59).
ss
the second with a leading zero or space (00-59).
zzz
the millisecond with a leading zero (000-999).
ampm
Specifies am or pm flag hours (0..12)
ap Specifies a or p flag hours (0..12)
(Any other character corresponds to a literal or delimiter.)
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
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)
1)
MyDate := DateTimeStrEval('dddd dd mmmm yyyy hh:nnampm (ss xxxx)', DT1);2)
MyDate := DateTimeStrEval('yyyymmdd', DT2);3)
MyDate := DateTimeStrEval('dd-mmm-yy', DT3);4)
MyDate := DateTimeStrEval('hh xxxx nn xxxxxx ss xxxxxx zzz xxxxx', DT4);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;
