Question

The Problem

Write a C or C++ program which performs specific operations on bits. The user will specify a value The user can then set, test, or toggle individual bits in the initial value.

Input

Your program will prompt the user for:

• An inital value in hexadecimal. This value may be up to 32 bits (eight hexadecimal digits) long. If the user-supplied value is less than eight characters in length, assume the additional digits are zero and are on the left side. Values longer than eight characters should be rejected.
• The desired operation: This can be the words "Test", "Set", "Toggle", or "End".
• For the "Test", "Set", and "Toggle" operations, a bit number must be provided. This must be in the range of zero to 31.
• For the "Set" operation, a new bit setting (0 or 1) must be provided.

If any any of the above values is incorrect, your program should prompt the user to re-enter the value until it is in the acceptable range.

Processing

Your program should perform the following steps:

1. Display message 1.
2. Display message 2 prompting the user for the input value.
3. Input the hexadecimal value. If it is longer than eight characters, display message 3 and return to the prior step.
4. Convert the hexadecimal character string to an unsigned int. If invalid hexadecimal characters are detected, display message 4 and return to step 2. Allow both upper and lower case characters.
5. Display message 6.
6. Input the user command. If it is not one of the valid commands, return to the prior step. Allow any combination of upper and lower case characters.
7. If the command is 'End', stop execution.
8. Issue message 7.
9. Input the bit number. If it is not in the range of zero to 31, return to the prior step.
10. Build a bit mask (an unsigned int which has only the specified bit set on).
11. If the command is 'Set';
    1. Issue message 10, then input the new bit value.
    2. If the new bit value is not 0 or 1, return to the prior step.
    3. If the new bit value is 1, perform a bitwise or operation on the hexadecimal value versus the bit mask.
    4. If the new bit value is 0, perform a bitwise and operation on the hexadecimal value versus the inverted bit mask.
    5. Issue message 8 showing the new hexadecimal value.
12. If the command is 'Test':
    1. Use a bitwise and operation to determine if the bit is on.
    2. Issue message 9 showing the result.
13. If the command is 'Toggle':
    1. Perform a bitwise exclusive or operation on the hexadecimal value versus the bit mask.
    2. Issue message 8 showing the new hexadecimal value.

Output

Message 1:

Pierce College CS516 Fall 2019 Lab Assignment 1 - Last, first

Replace Last, first with your name.

Message 2:

Enter the hexadecimal value, eight digits maximum

Message 3:

Value user's value is too long -- re-enter

Replace user's value with the value the user provided.

Message 4:

Digit digit is not valid, must be 0-9 or A-F, re-enter

Replace digit with the incorrect digit.

Message 5:

This message is omitted for this version of the assignment.

Message 6:

Enter 'Set' to change bits, 'Test' to check bit values, 'Toggle' to reverse a bit, or 'End' to finish

Message 7:

Enter bit number (0 to 31)

Message 8:

Value changed to XXXXXXXX

Replace XXXXXXXX with the new hexadecimal value.

Message 9:

Bit NN is binary value

Replace NN with the user-specified bit number, and binary value with 0 or 1.

Message 10:

Enter new bit value (0 or 1)

Sample Execution

Pierce College CS516 Fall 2019 Lab Assignment 1 - Murphy, J.H.

Enter the hexadecimal value, eight digits maximum

ABCDEF012

Value ABCDEF012 is too long -- re-enter

ABCDEG01

Digit G is not valid, must be 0-9 or A-Z, re-enter

ABCDEF01

Enter 'Set' to change bits, 'Test' to check bit values, 'Toggle' to reverse a bit, or 'End' to finish

Test

Enter bit number (0 to 31)

0

Bit 0 is 1

Enter 'Set' to change bits, 'Test' to check bit values, 'Toggle' to reverse a bit, or 'End' to finish

Set

Enter bit number (0 to 31)

3

Enter new Bit value

1

Value changed to ABCDEF09

Enter 'Set' to change bits, 'Test' to check bit values, 'Toggle' to reverse a bit, or 'End' to finish


End

Answer 1

Screenshot

Program

//Header files
#include <iostream>
#include<string>
#include<sstream>
#include<bitset>
using namespace std;

//Main method
int main()
{
   //Variable for input
   string hexVal;
   //Message1
   cout << "Pierce College CS516 Fall 2019 Lab Assignment 1 - Last, first\nReplace Last, first with your name." << endl;
   //Message 2
   cout << "Enter the hexadecimal value, eight digits maximum" << endl;
   cin >> hexVal;
   //Error check in input
   while (true) {
       bool flag = false;
       //Length check
       while (hexVal.length() > 8) {
           cout << "Value " << hexVal << " is too long -- re-enter" << endl;
           cin >> hexVal;
       }
       //Hex check
       for (int i = 0; i < hexVal.length(); i++) {
           if (!isdigit(hexVal[i]) && hexVal[i] != 'A' && hexVal[i] != 'B' && hexVal[i] != 'C' && hexVal[i] != 'D' && hexVal[i] != 'E' && hexVal[i] != 'F') {
               cout << "Digit " << hexVal[i] << " is not valid, must be 0-9 or A-Z, re-enter" << endl;
               flag = true;
               break;
           }
       }
       if (flag == false) {
           break;
       }
       cin >> hexVal;
   }
   //Convert into bit
   stringstream hexStream;
   hexStream << hex << hexVal;
   unsigned bits;
   hexStream >> bits;
   bitset<32> binHex(bits);
    //User prompt starts here
   string cmd;
   int bit,val;
   //Prompt for command
   cout << "Enter 'Set' to change bits, 'Test' to check bit values, 'Toggle' to reverse a bit, or 'End' to finish" << endl;
   cin >> cmd;
   //Loop unti user enter End
   while (cmd != "End") {
       //Test, return corresponding bit value
       if (cmd == "Test"){
           cout << "Enter bit number (0 to 31)" << endl;
           cin >> bit;
           cout << "Bit 0 is " << binHex[bit] << endl;
       }
       //set, change a bit
       else if (cmd == "Set") {
           cout << "Enter bit number (0 to 31)" << endl;
           cin >> bit;
           cout << "Enter new Bit value" << endl;
           cin >> val;
           binHex[bit] = val;
           stringstream result;
           result << hex << uppercase << binHex.to_ulong();
           cout << "Value changed to " << result.str() << endl;
       }
       //Toggle, change bit from 0 to 1 or 1 to 0
       else if (cmd == "Toggle") {
           cout << "Enter bit number (0 to 31)" << endl;
           cin >> bit;
           if (binHex[bit] == 0) {
               binHex[bit] = 1;
           }
           else {
               binHex[bit] = 0;
           }
           stringstream result;
           result << hex << uppercase << binHex.to_ulong();
           cout <<"Value changed to "<<result.str() << endl;
       }
       //Repetition part
       cout << "Enter 'Set' to change bits, 'Test' to check bit values, 'Toggle' to reverse a bit, or 'End' to finish" << endl;
       cin >> cmd;
   }
}

Output

Pierce College CS516 Fall 2019 Lab Assignment 1 - Last, first
Replace Last, first with your name.
Enter the hexadecimal value, eight digits maximum
ABCDEF012
Value ABCDEF012 is too long -- re-enter
ABCDEG01
Digit G is not valid, must be 0-9 or A-Z, re-enter
ABCDEF01
Enter 'Set' to change bits, 'Test' to check bit values, 'Toggle' to reverse a bit, or 'End' to finish
Test
Enter bit number (0 to 31)
0
Bit 0 is 1
Enter 'Set' to change bits, 'Test' to check bit values, 'Toggle' to reverse a bit, or 'End' to finish
Set
Enter bit number (0 to 31)
3
Enter new Bit value
1
Value changed to ABCDEF09
Enter 'Set' to change bits, 'Test' to check bit values, 'Toggle' to reverse a bit, or 'End' to finish
Toggle
Enter bit number (0 to 31)
3
Value changed to ABCDEF01
Enter 'Set' to change bits, 'Test' to check bit values, 'Toggle' to reverse a bit, or 'End' to finish
End