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--- fidonet:clang.ita [30/12/2024 06:13] – created lrosa
+++ fidonet:clang.ita [30/12/2024 14:27] (current) – lrosa
@@ Line 1: / Line 1: @@
+====== CLANG.ITA ======
+===== Descrizione =====
+Area italiana dedicata al linguaggio C.
+===== Messaggi interi =====
+==== Re: Struttura messaggi OPUS ====
+<code>
+Nov 89 15:54:00
+From:   Flavio Bernardotti
+To:     Luigi Rosa
+Subj:   Re: Struttura messaggi OPUS
+------------------------------------------------
+Ah sì? Ma Opus Pavia è in rete? Se sì, è quello di Martinelli?
+Ciao
+--- ITALMAIL v2.06
+ * Origin: ITALINK CBBS Montecastello (0131-355506)   (2:334/2)
+</code>
+==== FORMULA PER CALCOLO N.SETTIMANE ====
+<code>
+=============================================================================
+* Area : CLANG.ITA (Linguaggio C)
+* From : Salvatore Manzi, 2:332/108.7 (02 Apr 91 20:01)
+* To   : Duncan Wilcox
+* Subj : Congruenza di Zeller
+=============================================================================
+//                           by Jeff Duntemann
+//---------------------------------------------------------
+// calc_day_of_week calculates the day of the week using
+//   Zeller's Congruence, and returns a value from 0-6,
+//   where 0 = Sunday, 1 = Monday, and so on.
+//
+int calc_day_of_week(int year,
+             int month,
+             int day)
+{
+  int century, holder;
+  // First test for error conditions on input values:
+  if ((year < 0)  ||                   // Test for bad year
+      (month < 1) || (month > 12) ||   // Test for bad month
+      (day < 1)   || (day > 31))       // Test for bad day
+     return -1;             // Return -1 to indicate an error
+  else
+    /* Do the Zeller's Congruence calculation as Zeller himself */
+    /* described it in "Acta Mathematica" #7, Stockhold, 1887.  */
+    {
+      // First we separate out the year and the century figures:
+      century = year / 100;  // I.e., 19
+      year    = year % 100;  // I.e., 90
+      // Next we adjust the month such that March remains month #3,
+      //  but that January and February are months #13 and #14,
+      //  *but of the previous year*.  This is done to put the
+      //  weirdness of February at the *end* of the "year":
+      if (month < 3)   // Do this only for January & February!
+    {
+      month += 12;         // Increment month by 12
+      if (year > 0)        // The year before 2000 is
+        year -= 1;         //  1999, not 20-1, so
+      else                 //  so if the year is 00,
+        {                  //  we decrement the century
+          year = 99;       //  and make the year 99.
+          century -= 1;
+        };
+        };
+      // Here's Zeller's seminal black magic:
+      holder = day;                        // Start with the day of month
+      // This is a magic pill that figures the number of days that occur
+      //  prior to the start of the current month from *MARCH 1*:
+      holder = holder + (((month+1) * 26) / 10);
+      holder = holder + year;              // Add in the year
+      holder = holder + (year / 4);        // Correct for leap years
+      holder = holder + (century / 4);     // Correct for century years
+      holder = holder - century - century; // DON'T KNOW WHY HE DID THIS!
+      // modulus non fa altro che calcolare il modulo, non e' di libreria e per
+      // l'ho tolta
+      holder = modulus(holder,7);          // Take holder modulus 7
+      // Here we "wrap" Saturday around to be the last day:
+      if (holder == 0)
+    holder = 7;
+      // Zeller kept the Sunday = 1 origin; computer weenies prefer to
+      // start everything with 0, so here's a 20th Century kludge:
+      holder--;
+      return holder;  /* Return the end product! */
+    };
+};
+Nel tuo Main bastera' chiamare :calc_day_of_week(year,month,day);
+</code>