How to write an AutoIt script that calculate when it ran first time in a day?

Question

What would be an AutoIt script that should take the current time?

Answer 1

A function based way; formats result nicely and easy to understand:

#include <Date.au3>

Global $ini = "ini.ini"

If _AlreadyRunToday() Then
    MsgBox(0, "Title", _Format(_Diff()))
Else
    __SetTime()
EndIf
__SetDate()

Func _AlreadyRunToday() ;Checks if the program run today yet
    If IniRead($ini, "Section", "D", "") <> @MDAY _
            Or IniRead($ini, "Section", "M", "") <> @MON _
            Or IniRead($ini, "Section", "Y", "") <> @YEAR Then Return False
    Return True
EndFunc

Func _ReadDate() ;Returns the time when the program run the first time in YYYY/MM/DD HH:MM:SS
    Return IniRead($ini, "Section", "Y", "") & "/" & IniRead($ini, "Section", "M", "") & "/" & IniRead($ini, "Section", "D", "") & " " & IniRead($ini, "Section", "H", "") & ":" & IniRead($ini, "Section", "Mi", "") & ":" & IniRead($ini, "Section", "S", "")
EndFunc

Func __SetDate() ;Sets the date the program run the last time
    IniWrite($ini, "Section", "D", @MDAY)
    IniWrite($ini, "Section", "M", @MON)
    IniWrite($ini, "Section", "Y", @YEAR)
EndFunc

Func __SetTime() ;Sets the time of the first instance running that day
    IniWrite($ini, "Section", "H", @HOUR)
    IniWrite($ini, "Section", "Mi", @MIN)
    IniWrite($ini, "Section", "S", @SEC)
EndFunc

Func _Diff() ;Calculates the seconds passed since the first run today
    Return _DateDiff("s", _ReadDate(), _NowCalc())
EndFunc

Func _Format($Seconds) ;Turns seconds to HH:MM:SS
    Local $h, $m, $s
    _TicksToTime($Seconds * 1000, $h, $m, $s)
    ;Return $h & ":" & $m & ":" & $s
    Return StringFormat("%02d:%02d:%02d", $h, $m, $s) ;As suggested by Samoth
EndFunc