Finding the execution time of a program in pascal

Use the unit SysUtils and from that the Now() function - it will give you the current date and time. Call it once before and once after whatever you want to measure. Since TDateTime is in fact only a Double you can operate arithmetically on it (subtraction) - that way you can later just pull each time (and date) component to see how long it lasted:

program TimeDiff;

uses
  SysUtils;  // Every Pascal implementation should have this

// Just pointless calculations to waste CPU cycles
function RoutineToMeasure(): Integer;
var
  i, j: Integer;
begin
  result:= 0;
  for i:= 0 to $7FFFFFFF do begin
    j:= i div 24;
    j:= j+ 10;
    result:= result xor j;
    result:= result or i;
  end;
end;

// The actual program to measure times
var
  tStart, tEnd, tDiff: TDateTime;  // Begin and end of measurement, and difference
  iHours, iMinutes, iSeconds, iMilliseconds: Word;  // Time components
begin
  tStart:= Now();  // Get date+time
  RoutineToMeasure();
  tEnd:= Now();  // Get date+time again

  // To be read by a human
  Writeln( '  started: ', DateTimeToStr( tStart ) );
  Writeln( ' finished: ', DateTimeToStr( tEnd ) );

  // Calculating the actual time it took
  tDiff:= tEnd- tStart;  // Subtract higher from lower value
  DecodeTime( tDiff, iHours, iMinutes, iSeconds, iMilliseconds );  // Does not account for day changes when executing around midnight
  Writeln( '    taken: ', iHours, ' h, ', iMinutes, ' min, ', iSeconds, ' sec, ', iMilliseconds, ' msec' );

  Readln();
end.

Successfully tested in Lazarus 2.2.0 with FCP 3.2.2; the output is as per a 4 core 3.2 GHz CPU:

  started: 2022-12-14 14:33:07
 finished: 2022-12-14 14:33:12
    taken: 0 h, 0 min, 5 sec, 323 msec