Delphi/Lazarus: Date of yesterday

In addition to the function "now", there is also a function called "yesterday" available which can be used in the same way.

This function returns the date of yesterday as DateTime in which the time is set to 0:00h. Here is a small example:

var
  s: string;
  d: TDateTime;
begin
  d := Yesterday;
  s := FormatDateTime('yyyy-mm-dd', d);
  ShowMessage(s);
end; 

In order to use this function, you will have to add the unit DateUtils to your uses section.

FormatDateTime('yyyy-mm-dd', now - 1);

If you want to calculate the exact time exactly 24 hours ago or if you want to go without the Yesterday-function, you can also just substract 1 from Now. Because TDateTime is a decimal number with the days encoded before the decimal separator (1 corresponds to one day) and the time behind, this can be done without any problems.
Last update on 2021-04-02 | Created on 2017-02-26