Question

1. The Federal Bureau of Investigation (FBI) has recently changed its Universal Control Numbers (UCN) for identifying individuals who are in the FBI's fingerprint database to an eight-digit base 27 value with a ninth check digit. The digits used are: 0123456789ACDE FHJKLMNPRTVWX Some letters are not used because of possible confusion with other digits: B->8, G->C, I- >1, 0->0, Q->0, S->5, U->V, Y->V, 2->2 The check digit is computed as: (2 D14*D2+5*D3 +7 D4 +8 D5 10 D6+ 11 D7 13*D8) mod 27 Where Da is the nth digit from the left. This choice of check digit detects any single digit error and any error transposing an adjacent pair of the original eight digits. Write a C++ program to parse a UCN input by a user. The program should accept decimal digits and any capital letter as digits. If any of the confusing letters appear in the input, replace them with the corresponding valid digit as listed above. The program should compute the correct check digit and compare it to the entered check digit. The input isirejected if the first eight digits is returned they do not match otherwise the decimal (base 10) value corresponding The user will input a single line containing 9 decimal digits or capital (alphabetic) characters. The output will be one line consisting of the UCN number entered followed by the string "Invalid" (without the quotes) or the decimal value corresponding to the first eight digits. Use the C++ string class Refer to the sample output below. Sample Runs (2): Enter the UCN: 12345678A 12345678A decimal value is: 11280469652 Enter the UCN: 12435678A 12435678A- Invalid Name the program: FBINumbersXX.cpp, where XX are your initials.

Please I need help with this c++ code. please show all steps , write comments and show sample runs. Thank you.

Answer 1

#include<iostream>
#include<string.h>
#include<math.h>

using namespace std;

// function to get the desired integer value corresponding to each
// valid character specified in the definition
int lookupValue(char ch){

   int value ;

   switch(ch){
       case '0' : value = 0; break;
       case '1' : value = 1; break;
       case '2' : value = 2; break;
       case '3' : value = 3; break;
       case '4' : value = 4; break;
       case '5' : value = 5; break;
       case '6' : value = 6; break;
       case '7' : value = 7; break;
       case '8' : value = 8; break;
       case '9' : value = 9; break;
       case 'A' : value = 10; break;
       case 'C' : value = 11; break;
       case 'D' : value = 12; break;
       case 'E' : value = 13; break;
       case 'F' : value = 14; break;
       case 'H' : value = 15; break;
       case 'J' : value = 16; break;
       case 'K' : value = 17; break;
       case 'L' : value = 18; break;
       case 'M' : value = 19; break;
       case 'N' : value = 20; break;
       case 'P' : value = 21; break;
       case 'R' : value = 22; break;
       case 'T' : value = 23; break;
       case 'V' : value = 24; break;
       case 'W' : value = 25; break;
       case 'X' : value = 26; break;
       default : value = -1;
   }

   return value;
}

// function to replace the value of the characters
// which are confusing
char exchange(char ch) {

   char value;

   switch(ch){
       case 'B' : value = '8'; break;
       case 'G' : value = 'C'; break;
       case 'I' : value = '1'; break;
       case 'O' : value = '0'; break;
       case 'Q' : value = '0'; break;
       case 'S' : value = '5'; break;
       case 'U' : value = 'V'; break;
       case 'Y' : value = 'V'; break;
       case 'Z' : value = '2'; break;
       default : value = ch;
   }

   return value;
}

// function to convert base 27 number to base 10 number
long long int getBase10Value(string s){

   long long int value = 0;

   for(int i=0;i<8;i++){
       value += lookupValue(s[i])*pow(27,7-i);
   }

   return value;
}

// function to validate if the value of the number we get using the formula
// matches the check bit
bool validateCheckSum(string s){

   int sum = 0;
   sum += 2*lookupValue(s[0]);
   sum += 4*lookupValue(s[1]);
   sum += 5*lookupValue(s[2]);
   sum += 7*lookupValue(s[3]);
   sum += 8*lookupValue(s[4]);
   sum += 10*lookupValue(s[5]);
   sum += 11*lookupValue(s[6]);
   sum += 13*lookupValue(s[7]);
   sum = sum % 27;

   if(sum == lookupValue(s[8])){
       return true;
   }else{
       return false;  
   }
  
}

int main(){

   string ucn;

   cout<<"Enter the UCN : ";
   cin>>ucn;

   // for loop to replace conflict characters
   for(int i=0;i<9;i++){
       ucn[i] = exchange(ucn[i]);  
   }

   // validating check sum and printing output
   if(validateCheckSum(ucn)){
       cout<<ucn<<" decimal value is : "<<getBase10Value(ucn)<<endl;
   }else {
       cout<<ucn<<"- Invalid"<<endl;
   }

   return 0;
}