Expt 1 - Part 1, Part 2 & Part 3

Explanation

This Java program is designed to calculate and display the sum of all elements stored within an integer array. It initializes an array with a predefined set of numbers. It then uses a fundamental programming construct called a "for loop" to systematically go through each number in the array, adding it to a running total. Finally, once all numbers have been processed, it prints the accumulated sum to the console.

Here's a step-by-step breakdown of the logic:

1. Class Definition: The code starts by defining a class named sum_of_elements. In Java, all executable code resides within classes.
2. Main Method: Inside the class, there's a main method (public static void main(String[] args)). This is the entry point of any Java application; when you run the program, execution begins here.
3. Array Initialization: An integer array named arr is declared and immediately initialized with the values 1, 2, 3, 4, 5. This means arr now holds these five numbers in sequence.
4. Sum Variable Initialization: An integer variable named sum is declared and initialized to 0. This variable will be used to store the total sum of the array elements as they are processed. It's crucial to start it at zero so that the first addition is accurate.
5. Looping Through the Array: A for loop is used to iterate over each element of the arr array.
   • int i = 0: The loop counter i starts at 0, which is the index of the first element in the array.
   • i < arr.length: The loop continues as long as i is less than the total number of elements in the array (arr.length will be 5). This ensures every element from index 0 to 4 is visited.
   • i++: After each iteration, the value of i is incremented by 1, moving to the next element in the array.
6. Accumulating the Sum: Inside the loop, the statement sum += arr[i]; does the core calculation. It takes the value of the current element (arr[i]) and adds it to the existing value of the sum variable. This operation updates sum with the running total.
7. Printing the Result: Once the loop has finished executing (meaning all elements have been added to sum), the program moves to the next line. System.out.println("Sum of elements of array: " + sum); prints a descriptive string "Sum of elements of array: " followed by the final calculated value stored in the sum variable to the console.

Algorithm

The algorithm used in this program to calculate the sum of array elements can be described as follows:

1. Declare and Initialize Array: Define an integer array and populate it with the numbers whose sum needs to be calculated.
2. Initialize Sum Variable: Create an integer variable (e.g., sum) and set its initial value to zero. This variable will accumulate the sum.
3. Iterate Through Array: Start a loop that will visit each element of the array, from the first element (index 0) to the last element.
4. Add Element to Sum: Inside the loop, for each element visited, add its value to the sum variable.
5. Display Result: After the loop has completed processing all elements, print the final value stored in the sum variable.