Sign in Join
FPDoc Onlineexperiment

WithinPastMilliSeconds function

In unit DateUtils

Check whether two TDateTimes are only a number of milliseconds apart.

Declaration

pascal
function WithinPastMilliSeconds(const ANow: TDateTime; 
 const AThen: TDateTime; 
 const AMilliSeconds: Int64): Boolean

Arguments

ANow

First moment in time.

AThen

Second moment in time.

AMilliSeconds

Number of milliseconds to check.

Function result

True if ANow and Athen are only AMilliSeconds apart, false otherwise.

Description

WithinPastMilliSeconds compares the timestamps ANow and AThen and returns True if the difference between them is at most AMilliSeconds milliseconds apart, or False if they are further apart.

Since this function uses the MilliSecondsBetween function to calculate the difference in milliseconds, this means that fractional milliseconds do not count, and the fractional part is simply dropped, so for two dates actually 2 and a half milliseconds apart, the result will also be True

See also

Example: ex54

pascal
Program Example54;

{ This program demonstrates the WithinPastMilliSeconds function }

Uses SysUtils,DateUtils;

Procedure Test(ANow,AThen : TDateTime; AMilliSeconds : Integer);

begin
 Write(TimeToStr(AThen),' and ',TimeToStr(ANow));
 Write(' are within ',AMilliSeconds,' milliseconds: ');
 Writeln(WithinPastMilliSeconds(ANow,AThen,AMilliSeconds));
end;

Var
  D1,D2 : TDateTime;

Begin
  D1:=Now;
  D2:=D1-(0.9*OneMilliSecond);
  Test(D1,D2,1);
  D2:=D1-(1.0*OneMilliSecond);
  Test(D1,D2,1);
  D2:=D1-(1.1*OneMilliSecond);
  Test(D1,D2,1);
  D2:=D1-(2.5*OneMilliSecond);
  Test(D1,D2,1);
  Test(D1,D2,2);
  Test(D1,D2,3);
End.

An experiment, built from development snapshots. Not the official Free Pascal or Lazarus documentation.