9.7.1. Arrays-WE6-P1

Subgoals for Evaluating Arrays

1. Set up array from 0 to size-1

2. Evaluate data type of statements against array

3. Trace statements, updating slots as you go

   1. Remember assignment subgoals

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Arrays-WE6-P1

Put the following code in order to create a program that will declare and instantiate an array of 20 random values between 1 and 100 and then calculate and print the average of the first 10 numbers.

        import java.util.*;
public class main{
   public static void main (String[] args) {
---
      Random r = new Random();
      int [] arr = new int[20];
---
      for (int i = 0; i < 20; i++) {
         arr[i] = r.nextInt(100) + 1;
         System.out.println("arr["+i+"] is " + arr[i]);
      }
---
      int sum = 0;
---
      for (int i = 0; i < 10; i++) {
---
         sum += arr[i];
---
      }
---
      System.out.println("Avg of first 10 is " + sum/10.0);
---
   }
}
        

Put the following code in order to create a program that will declare and instantiate an array of 20 random values between 1 and 100 and then calculate and print the average of the last n numbers.

        import java.util.*;
public class main{
   public static void main (String[] args) {
---
      Random r = new Random();
      int [] arr = new int[20];
---
      for (int i = 0; i < 20; i++) {
         arr[i] = r.nextInt(100) + 1;
         System.out.println("arr["+i+"] is " + arr[i]);
      }
---
      int sum = 0;
---
      for (int i = 20-n; i < 20; i++) {
---
         sum += arr[i];
---
      }
---
      if (n > 0)
---
         System.out.println("Avg of last n is " + (sum * 1.0)/n);
---
      else
---
         System.out.println("No numbers to average.")
---
   }
}
        

public class main{ public static void main(String args[]){ } }

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