Differenze tra le versioni di "Sapere quanti secondi sono passati dall'inizio dell'anno corrente"

Versione delle 18:30, 7 nov 2014

Per sapere quanti secondi sono trascorsi dall'inizio del corrente anno, è possibile utilizzare alcune funzioni esterne della libreria time.h di C, come segue:

Public Struct tm
  tm_sec As Integer      ' secondi (0 - 59)
  tm_min As Integer      ' minuti (0 - 59)
  tm_hour As Integer     ' ore (0 - 23)
  tm_mday As Integer     ' Giorno del mese (1 - 31)
  tm_mon As Integer      ' Mese (1 - 12)
  tm_year As Integer     ' Anno (numero di anni dal 1900)
  tm_wday As Integer     ' Giorno della Settimana (0 - 6)
  tm_yday As Integer     ' Giorno nell'Anno (0 - 365)
  tm_isdst As Integer    ' ora legale
End Struct

Library "libc:6"

' time_t time (time_t* timer)
' Get the current calendar time as a value of type time_t.
' The value returned generally represents the number of seconds since 00:00 hours, Jan 1, 1970 UTC (i.e., the current unix timestamp).
Private Extern Time_C(timerptr As Pointer) As Long Exec "time"

' tm* localtime( const time_t *time )
' Converts given time since epoch as time_t value into calendar time, expressed in local time.
Private Extern localtime(tm As Pointer) As Pointer

' double difftime (time_t end, time_t beginning)
' Returns the number of seconds elapsed between time time1 and time time0, represented as a double.
Private Extern difftime(endl As Long, beginningl As Long) As Float

' time_t mktime(struct tm *timeptr)
' Converts the structure pointed to by timeptr into a time_t value according to the local time zone.
Private Extern mktime(timerptr As Tm) As Long

 
Public Sub Main()

 Dim tempus As New Tm
 Dim t As Long
 Dim sec As Float
 
  Time_C(VarPtr(t))

  tempus = localtime(VarPtr(t))

  With tempus
    .tm_mon = 0
    .tm_mday = 1
    .tm_hour = 0
    .tm_min = 0
    .tm_sec = 0
  End With

  sec = difftime(t, mktime(tempus))

  Print "Secondi trascorsi sino ad oggi dall'inizio dell'anno corrente:  "; sec

End