Question

1. Maintain two arrays for use in “translating” regular text to “leetspeak”:

(a) One array will contain the standard characters:

char[] letters = {'a', 'e', 'l', 'o', 's', 't'}; (b) The other will contain the corresponding symbols:

char[] symbols = {'@', '3', '1', '0', '$', '7'};

2. Prompt the user to enter a full sentence with all lower-case characters, then store it in a variable to be

used later.

(a) You can (optionally) manually convert the string to all lower-case with the String method called

toLowerCase(), for example:

String one = "Hello, World!";

String two = one.toLowerCase(); System.out.println(two); // Output: hello, world!

3. Convert the input string to an array of characters.

4. Then, use a loop to iterate the array of characters and, for each one, check to see if it is in the letters

array: if it is, replace with the corresponding element (i.e. same index) in the symbols array. (a) For example, if the user inputs leetspeak the output should be 1337$p3@k.

2

5. Next,“reset”thecharacterarraytomatchtheoriginalinputstring–youcanjustusethe.toCharArray() command again.

6. Now, prompt the user for a positive integer, store it in a variable. This will be a shift for a basic “Caesar Cipher”.

7. Finally, loop the character array and, if the character is not a space, display: (a) Show the character itself

(b) Show the corresponding ASCII code by converting it to an int. See the following example code of type casting between int and char:

char myChar = 'd';

int myInt = 5;

int combined = myChar + myInt;

System.out.println(myChar); // d

System.out.println((int) myChar); // 100

// NB: when doing addition, they become an int if you don't specify System.out.println(myChar + myInt) // 105

System.out.println((char) combined); // i

(c) Show the result of adding the user’s integer to the ASCII code and converting back to a char.

i. When you add, you want to “wrap around” from z back to a. So to accommodate this, you can use the modulus operator, % along with some clever arithmetic.

ii. For example, if the user enters 5 for the shift value, and you have the character x (ASCII value 120), the result should be c (ASCII value 99); likewise, if the character is b (ASCII value 97) the result would be g (ASCII value 103).

8. Either with a new for-loop, or in the one above, change the elements of the character array by adding the integer to each one. Then display the “shifted” sentence to the user. This is known as the “Caesar Cipher”, and was an early form of sending encrypted messages; you just need to know what the shift value was in the beginning, then subtract it out from the message you receive!

Java

Answer 1

import java.util.Scanner;
class Main
{
        public static void main (String[] args)
        {
            // Part 1
            char[] letters = {'a', 'e', 'l', 'o', 's', 't'}; 
        char[] symbols = {'@', '3', '1', '0', '$', '7'};
        
        // Part 2
                Scanner sc = new Scanner(System.in);
                System.out.println("Enter sentence in lower case");
                String str = sc.nextLine();
                str = str.toLowerCase(); 
                
                // Part 3
                char arr[] = str.toCharArray();
                
                // Part 4
                String new_str = "";
                int flag=0;
                for(int i=0;i<arr.length;i++){
                    flag=0;
                    for(int j=0;j<letters.length;j++){
                        if(arr[i]==letters[j]){
                            new_str+=symbols[j];
                            flag=1;
                            break;
                        }
                    }
                    if(flag==0)
                        new_str+=arr[i];
                }
        System.out.println(new_str);
        
        // Part 5
        char array[] = str.toCharArray();
        
        // Part 6
        System.out.print("Enter a number for shifting the text: ");
        int shift = sc.nextInt();
        
        // Part 7
    char tempstr;
    String finalstr="";
        for(int i=0;i<array.length;i++){
            if(array[i]!= ' '){
                int combined = array[i] + shift;
                int element = combined-97;
                element = element%26;
                combined = element+97;
            System.out.println(array[i]);
            System.out.println(combined);
            System.out.println((char) combined);
            tempstr = (char)combined;
            }
            else
                tempstr = ' ';
           finalstr += tempstr;   
        }
        
        // Part 8
        System.out.println(finalstr);
        
        }
}

NOTE: The above code is in Java. Please refer to the attached screenshots for code indentation and sample I/O.

SAMPLE I/O: