more work porting, day of week calculation works

95_Weekday/rust/src/main.rs

@@ -7,7 +7,15 @@ struct DATE {
     day_of_week:u32,
 }
 impl DATE {
-    //create one from user input
+    /**
+     * create new date with given paramets
+     */
+    fn new(month:u32,day:u32,year:u32,day_of_week:u32) -> DATE {
+        return DATE { month: month, day: day, year: year, day_of_week: day_of_week };
+    }
+    /**
+     * create date from user input
+     */
     fn new_from_input(prompt:&str) -> DATE {
         //DATA
         let mut raw_date: Vec<u32>;
@@ -46,31 +54,27 @@ impl DATE {
 
     /**
      * caluclates the day of the week (1-7)
+     * uses the methodology found here: https://cs.uwaterloo.ca/~alopez-o/math-faq/node73.html
      */
     fn update_day_of_week(&mut self) {
-        let month_table:[u32;12] = [0, 3, 3, 6, 1, 4, 6, 2, 5, 0, 3, 5];
-        let i1 = (self.year - 1500) / 100;
-        let a = i1 * 5 + (i1 + 3)/4;
-        let i2 = a - (a/7) * 7;
-        let y2 = self.year/100;
-        let y3 = self.year - y2*100;
-        let a = y3 / 4 + y3 + self.day + month_table[(self.month - 1) as usize] + i2;
-        let  b = a - (a/7) * 7;
-
-        //adjust weekday and set it
-        if self.month <= 2 && self.is_leap_year() {
-            self.day_of_week = b-1;
+        let day = self.day as isize;
+        let month = self.month as isize;
+        let year = self.year as isize;
+        let century = year/100;
+        let year_of_century = year - century*100;
+        let weekday; //as 0-6
+        if self.month <= 2 { //if jan or feb
+            weekday = (day + (2.6 * ((month+10) as f64)-0.2)as isize - 2*century + (year_of_century-1) + (year_of_century-1)/4 + century/4) % 7;
         } else {
-            self.day_of_week = b;
+            weekday = (day + (2.6 * ((month-2)  as f64)-0.2)as isize - 2*century + year_of_century     + year_of_century/4     + century/4) % 7;
         }
-        if self.day_of_week == 0 {self.day_of_week = 7;}
-
+        self.day_of_week=(weekday+1) as u32; //weekday as 1-7
     }
 
     /**
      * is the year a leap_year
      */
-    fn is_leap_year(&self) -> bool{
+    fn _is_leap_year(&self) -> bool{
         if self.year % 4 != 0 {
             return false;
         } else if self.year %100 != 0 {
@@ -81,23 +85,55 @@ impl DATE {
             return true;
         }
     }
+
+    /**
+     * calculates the day value, number of days the date represents
+     */
+    fn calc_day_value(&self) -> u32 {
+        return (self.year*12 + self.month)*31 + self.day;
+    }
+
+    /**
+     * returns true if passed date is before this date, false otherwise
+     */
+    fn is_after(&self,other:&DATE) -> bool {
+        if self.calc_day_value() > other.calc_day_value() {
+            return true;
+        }
+        else {
+            return false;
+        }
+    }
 }
+impl ToString for DATE {
+    fn to_string(&self) -> String {
+        return format!("{}/{}/{}",self.month,self.day,self.year);
+    }
+}
+
+
 fn main() {
     //DATA
-    let todays_date: DATE;
+    let today_date: DATE;
     let other_date:DATE;
+    let delta_date:DATE; //represents the difference between the two dates
+    let today_value;
+    let other_day_value;
+    let mut other_is_today = false;
 
     //print welcome
     welcome();
-
+    
     //get todays date
-    todays_date = DATE::new_from_input("ENTER TODAY'S DATE IN THE FORM: 3,24,1979  ");
+    today_date = DATE::new_from_input("ENTER TODAY'S DATE IN THE FORM: 3,24,1979  ");
     //check todays date
-    if todays_date.year < 1582 {
+    if today_date.year < 1582 {
         println!("NOT PREPARED TO GIVE DAY OF WEEK PRIOR TO MDLXXXII.");
         return;
     }
 
+    println!();
+
     //get other date
     other_date = DATE::new_from_input("ENTER DAY OF BIRTH (OR OTHER DAY OF INTEREST) (like MM,DD,YYYY)");
     //check other date
@@ -106,6 +142,49 @@ fn main() {
         return;
     }
 
+    //do some calculations
+    today_value = today_date.calc_day_value();
+    other_day_value = other_date.calc_day_value();
+
+    //print the other date in a nice format
+    println!(
+        "{} {} A {}",
+        other_date.to_string(),
+        { //use proper tense of To Be
+            if today_value < other_day_value {"WILL BE"}
+            else if today_value == other_day_value {other_is_today=true;"IS A"}
+            else {"WAS A"}
+        },
+        other_date.day_of_week,
+    );
+
+    //do nothing if both days are the same, or if the other date is after the first
+    if other_is_today || other_date.is_after(&today_date) {
+        return;
+    } 
+
+    //create date representing the difference between the two dates
+    delta_date = DATE::new( //OVERFLOW ERROR, FIX LATER
+        today_date.month - other_date.month,
+        today_date.day - other_date.day,
+        today_date.year - other_date.year,
+        0
+    );
+
+    //print happy birthday message
+    if delta_date.month == 0 && delta_date.day == 0 {
+        println!("***HAPPY BIRTHDAY***");
+    }
+
+    //print report
+    print!("
+                      \tYEARS\tMONTHS\tDAYS
+                      \t-----\t------\t----
+    ");
+    println!("YOUR AGE (IF BIRTHDATE)\t{}\t{}\t{}", delta_date.year,delta_date.month,delta_date.day);
+
+
+
 }