Symbol Reference > .Net Native Interface Library > API Functions > .Net DateTime Functions > DateTime

Returns a system DateTime equivalent to the specified OLE AutomationDate.

C/C++ Syntax

extern "C" HRESULT __stdcall DateTime_FromOADate(ClrDouble DateTimeAsDouble, ClrDateTime &DateTime);

Pascal Syntax

function DateTime_FromOADate(DateTimeAsDouble: ClrDouble; var DateTime: ClrDateTime): HRESULT; stdcall;

Parameters

DateTimeAsDouble

Type: ClrDouble

An OLE Automation Date value.

DateTime

Type: ClrDateTime

An object that represents the same date and time as DateTimeAsDouble.

Return Value

Type: HRESULT

If the function succeeds, the return value is zero.
If the function fails, the return value is the error code. To get extended error information, call Exception_GetExceptionForErrorCode.

Exceptions

System.ArgumentException

The date is not a valid OLE Automation Date value.

Remarks

The DateTimeAsDouble parameter is a double-precision floating-pointnumber that represents a date as the number of days before or after thebase date, midnight, 30 December 1899. The sign and integral part ofDateTimeAsDouble encode the date as a positive or negative daydisplacement from 30 December 1899, and the absolute value of thefractional part of DateTimeAsDouble encodes the time of day as a fractionof a day displacement from midnight. DateTimeAsDouble must be a valuebetween negative 657435.0 through positive 2958465.99999999.

Note that because of the way dates are encoded, there are two ways ofrepresenting any time of day on 30 December 1899. For example, -0.5 and0.5 both mean noon on 30 December 1899 because a day displacement of plusor minus zero days from the base date is still the base date, and a halfday displacement from midnight is noon.

Examples

The following example uses the DateTime_FromOADate method to instantiate a new DateTime value.

C/C++

int main(int argc, char** argv) {

ClrDateTime m_sysDate;

double m_date = 50424.134803241; /* 19-Jan-2038 03:14:07 */
HRESULT m_result = DateTime_FromOADate(m_date, m_sysDate);
if (m_result == CLR_OK) {
int m_bufferLen = DateTime_ToString(m_sysDate, NULL, NULL, 0);
wchar_t *m_buffer = new wchar_t[m_bufferLen + 1];
DateTime_ToString(m_sysDate, NULL, m_buffer, m_bufferLen);
std::wcout << m_buffer << std::endl;
delete[] m_buffer;
}

return 0;
}

Object Pascal

var
m_result: HResult;
m_sysDate: ClrDateTime;
m_date: TDateTime;
m_bufferLen: Integer;
m_buffer: PWideChar;
begin
m_date := 50424.134803241; /* 19-Jan-2038 03:14:07 */
m_result := DateTime_FromOADate(m_date, m_sysDate);
if m_result = CLR_OK then
begin
m_bufferLen := DateTime_ToString(m_sysDate, nil, nil, 0);
GetMem(m_buffer, m_bufferLen);
try
DateTime_ToString(m_sysDate, nil, m_buffer, m_bufferLen);
Writeln(string(m_buffer));
finally
FreeMem(m_buffer);
end;
end;
end.

Reference

•DotNetNativeInterface

DateTime_FromOADate(ClrDouble,ClrDateTime) Method

DateTime_FromOADate(ClrDouble,ClrDateTime) Method

Return Value