Question

Please write this code in C++, also if you could please bold the names of the input files and provide comments for each choice.

For this part, the program gives the user 4 choices for encrypting (or decrypting) the first character of a file. Non-lowercase characters are simply echoed. The encryption is only performed on lowercase characters.

• If c is char variable, then islower(c) will return true if c contains an lowercase character, false otherwise
• To read a single character from a file (let inFile be the name of your ifstream), you can use: inFile.get(c);
  • This will read one character, even the whitespace characters
• Choice 1 – No encryption, echo the character from the file
• Choice 2 – Encrypt by shifting. For example, shifting by 3 characters would change an ‘a’ to a ‘d’ because that is 3 letters later. If you reach the end of the alphabet then you need to roll over. For example ‘z’ plus 3 is ‘c’.
  • NOTE: The process of converting the ‘z’ to a ‘c’ should NOT need the use of an if, switch, or loop statement.
  • For this week, you may use an if or switch if you need, but next week you’ll have to do it without
• Choice 3 – This is the opposite of choice 2. Instead of moving 3 letters forward, it will move 3 letters backwards. A ‘d’ will become ‘a’.
  • Like choice 2, the shifting can be accomplished without if’s, switch’s, and loop’s.
• Choice 4 – This will calculate a hash value. You sum the ASCII values of all of the characters and at the end of the file print the last 2 digits of the sum. For example, “abc” is 94 because ‘a’ is 97, ‘b’ is 98, ‘c’ is 99, which has a sum of 294.
  • Remember, this week we are only reading a single character
• Your program should prompt the user for:
  • The encryption type
  • The name of a file
  • For this week, the prompt will be very short, just a ?
• Your program should output the encrypted characters (or a hash value).

This is the input files named file1.txt and file2.txt

• file1.txt has the following contents:

yippee

• file2.txt has the following contents:

A-bba cc
xyyz

This is what the user is typing it's in bold, and the output is under it.

Sample Run #1 (bold, underlined text is what the user types):

? 1 file1.txt

y

Sample Run #2 (bold, underlined text is what the user types):

? 2 file1.txt

b

Sample Run #3 (bold, underlined text is what the user types):

? 3 file1.txt

v

Sample Run #4 (bold, underlined text is what the user types):

? 4 file1.txt

21

Sample Run #5 (bold, underlined text is what the user types):

? 1 file2.txt

A

Sample Run #6 (bold, underlined text is what the user types):

? 2 file2.txt

A

Sample Run #7 (bold, underlined text is what the user types):

? 4 file2.txt

0

Answer 1

Code:

#include <iostream>
#include <string>
#include <fstream>
using namespace std;

int main()
{
   int choice; // stores user choice of encryption
   string fileName; // stores filename
   // prompting user
   cout << "? ";
   cin >> choice >> fileName;

   // opens the file
   ifstream inFile;
   inFile.open(fileName.c_str());

   char c; // character from file
   inFile.get(c); // reading first character from file
   bool lower = islower(c); // if it's lowercase
   char c_new;

   if (choice == 1) // if user chooses print character
   {
       // printing first character
       cout << endl << c << endl;
   }
   else if (choice == 2 && lower) // if user chooses to shift forward and character is lowercase
   {
       c_new = (((int)c - 97) + 3)%26 + 97;
       cout << endl << c_new << endl;
   }
   else if (choice == 3 && lower) // if user chooses to shift backward and character is lowercase
   {
       if (c > 'c')
       {
           c_new = (((int)c - 97) - 3)%26 + 97;
       }
       else if (c == 'a')
       {
           c_new = 'x';
       }
       else if (c == 'b')
       {
           c_new = 'y';
       }
       else
       {
           c_new = 'z';
       }
       cout << endl << c_new << endl;
   }
   else if (choice == 4 && lower) // if user chooses to print last two digits of ascii value
   {
       cout << endl << (int)c%100 << endl;
   }
   else if (choice == 4 && !lower) // if character is upper case
   {
       cout << endl << 0 << endl;
   }
   else // if character is upper case
   {
       cout << endl << c << endl;
   }

   // closing file
   inFile.close();

   return 0;
}

OUTPUT: