Expt 1 - Part 1, Part 2 & Part 3

Explanation

This Java program is designed to take a string input from the user, reverse the order of its characters, and then convert the entire reversed string to uppercase.

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

1. Import Scanner: It first imports the Scanner class, which is necessary to read input from the console (like keyboard input).
2. Create Scanner Object: Inside the main method, an object of the Scanner class is created, allowing the program to read input from System.in (the standard input stream, typically the keyboard).
3. Prompt User: The program then displays a message "Enter a string: " on the console, prompting the user to type something.
4. Read Input: Whatever the user types until they press Enter is read as a complete line and stored in a String variable named input.
5. Initialize Reversed String: An empty String variable named reversed is created. This variable will be used to build the reversed string character by character.
6. Reverse Loop: A for loop is initiated. This loop starts iterating from the last character of the input string (index input.length() - 1) and goes backward, character by character, until it reaches the first character (index 0).
   • In each iteration, input.charAt(i) extracts the character at the current index i from the original input string.
   • This extracted character is then appended to the reversed string using the += operator.
7. Convert to Uppercase: After the loop finishes, the reversed string now holds the completely reversed version of the original input. The program then calls the toUpperCase() method on this reversed string. This method returns a new string where all characters are converted to their uppercase equivalents, and this new string is stored in the result variable.
8. Display Output: Finally, the program prints the message "Reversed and Uppercase String: " followed by the content of the result string to the console.
9. Close Scanner: The scanner.close() method is called to release the system resources associated with the Scanner object, which is good programming practice.

Algorithm

The algorithm implemented in this program can be described as follows:

1. Start the program execution.
2. Create a Scanner object to read input from the console.
3. Display a prompt asking the user to enter a string.
4. Read the entire line of text entered by the user and store it in a string variable (e.g., input).
5. Initialize an empty string variable (e.g., reversed) to store the reversed string.
6. Iterate through the input string using a for loop, starting from the last character's index (input.length() - 1) and decrementing the index until it reaches 0.
7. In each iteration of the loop:
   • Retrieve the character at the current index i from the input string.
   • Append this character to the reversed string.
8. Once the loop completes, the reversed string will contain the original string in reverse order.
9. Convert the reversed string to its uppercase equivalent using the toUpperCase() method and store it in a new string variable (e.g., result).
10. Print the result string along with an informative label to the console.
11. Close the Scanner object to release system resources.
12. End the program.