// Exercises from Lecture 3

// computing a sum

class Loops {
   static void Main() {
      int n = 10;
      int[] arr = {1,2,3,4,5,6,7,8,9,10};
      System.Console.WriteLine("Testing some loops now...");
      int s1 = Loops.Sum1(n);
      System.Console.WriteLine("Sum from 1 to "+n+" = "+s1);
      int s2 = Loops.Sum2(n);
      System.Console.WriteLine("Sum from 1 to "+n+" = "+s2);
      int sa1 = Loops.SumArr1(arr);
      System.Console.WriteLine("SumArr = "+sa1);
      int sa2 = Loops.SumArr2(arr);
      System.Console.WriteLine("SumArr = "+sa2);
      /*
      int[] arrr = new int[10];
      int i;
      for (i=0; i<10; i++) { // beware of indices
        arrr[i]=i-1;
      }
      Loops.SumArr(arrr);
      */
   }
   static int Sum1(int n) {
     int i = 1, s = 0;
     while (i<=n) {
       s += i;
       i++;
     }
     return s;
   }
   static int Sum2(int n) {
     int i = 1, s = 0;
     for (i=0; i<=n; i++) {
       s += i;
     }
     return s;
   }
   static int SumArr1(int[] arr) {
     int i, s = 0;
     for (i=0; i<arr.Length; i++) { // conventional iteration
       s+=arr[i];
     }
     return s;
   }
   static int SumArr2(int[] arr) {
     int s = 0;
     foreach (int v in arr) { // no indices needed here
       s+=v;
     }
     return s;
   }
}