Question

I need it in c++

The U.S. Banking System

The code assigned to a bank is an eight digit number plus a ninth check
digit. To check for validity, the first eight digits are assigned weights
(left to right) of 7, 3, and 9 repetitively. Each digit is multiplied by
its weight and the products summed. The resulting sum (mod 10) should
equal the check digit.  The assigning of weights insures that all single
digit errors and most transposition errors are detected.

You should run the program twice, once using a valid bank number, and once
using an invalid bank number.

   103000648  Chase 
   103000846  Chase with a transposition error
   103000703  Interbank
   103001469  Kirkpatrick Bank
   103002251  Citizens Bank of Edmond 
   103002521  Citizens Bank of Edmond with a transposition error 
   103002691  First Fidelity
   103002795  First Commercial Bank with an error
   103003632  Banc First
   103003687  First Commercial Bank 
   103013062    "
   103013101    "
   103013266  PRIME BANK  1016 W Covell Road
   103112594  RCB Edmond Road
   103112976  Arvest
   303085230  Allegiance Credit Union
   303085829  Tinker Federal Credit Union 
   303087995  Mid First 
   300387995  Mid First with a transposition error
   103900036  Bank of Oklahoma
   081904808  Bank of America  2145 W Edmond Rd
              Spirit Bank  3823 S Boulevard
              Farmers & Merchants 121 E Waterloo
              Legacy  1289 E 15
              Bank of Nichols Hills



Sample Logic:
  read in a bank number
  write the bank number, and the multipliers 
  compute the checksum
    loop 8 times using i as a control variable
      pick off the i'th digit
        ch = bank number[i] 
        digit[i]  = ch-48;
      multiply it by the appropriate weight
      print the product
      add the product to the subtotal
      save the subtotal in an array (in subtotal[i]) 
    end loop
  loop 8 times printing the subtotals
  print the last subtotal computed
  compute the check digit
  print the check digit 
  if the subtotal % 10 == the last digit
  then
    write 'the check code is valid'
  else
    write 'the check code is invalid'


Sample output:
  - print these numbers - -     don't print these words
  1  0  3  0  0  0  6  4  8     bank number
  7  3  9  7  3  9  7  3        multipliers
  7  0 27  0  0  0 42 12        products
  7  7 34 34 34 34 76 88        subtotals
  88                            sum
  8                             check digit
  the check code is valid

Answer 1

The above problem can be solved in the following steps-

STEP 1- Read the algorithm carefully given in question and then write C++ code accrodingly.

STEP 2- Read bank number from user and store it in string variable. Store the 8 digit multiplier as constant 73973973. Then create two arrays to store digits and subtotals of size 8.

STEP 3- Write the bank numbers and multipliers as output.

STEP 4-Loop 8 times with i as control variable and do the following-

• pick the i'th digit from bankNumber and store it in digit array by changing it to integer.
• store the weight also for corresponding index i.
• compute the product by multiplying the weight and digit. And print the product.
• compute and store subtotals in subtotal array.

STEP 5- Loop 8 times and print the subtotals.

STEP 6-Print the last subtotal. Then compute the check digit and then print this check digit.

STEP 7-Finally, using if-else check if last subtotal%10 is equal to check digit. If yes then print valid check code otherwise print invalid check code.

C++ CODE-

//include neccessary header files
#include <iostream>
using namespace std;
//driver method
int main()
{
//variable to store bankNumber
string bankNumber;
//read bank number from user
cin>>bankNumber;
//from here on everything is part of output
cout<<"\n-------OUTPUT-----------\n";
//store the multipliers in a variable
//multipliers is always fixed that is why its store as constant here
string multipliers = "73973973";
//arrays to store the digits and subtotal
int digit[8];
int subtotal[8];
//write the bank number
cout<<bankNumber<<endl;
//write the multipliers
cout<<multipliers<<endl;
//loop 8 times using i as control variable
for(int i=0;i<8;i++){
//pick of i'th digit
char ch = bankNumber[i];
digit[i] = ch - 48;
  
//store weight by converting multipliers character to integer
int weight = multipliers[i]-48;
//multiply it by the appropriate weight
int product = digit[i] * weight;
//print the product
cout<<product<<" ";
//adding product to subtotal
//if its first subtotal, then put product directly to 0th index
if(i==0){
subtotal[i] = product;
}
//otherwise, subtotal is equal to product + previous index subtotal
else{
subtotal[i] = subtotal[i-1] + product;
}
}
//newline
cout<<endl;
//loop 8 times printing the subtotals
for(int i=0;i<8;i++){
cout<<subtotal[i]<<" ";
}
//newline
cout<<endl;
//print the last subtotal computed
//since subtotal array is of size 8
//last subtotal will be at index 7 of subtotal array
cout<<subtotal[7]<<endl;
  
//compute the check digit
int checkDigit = bankNumber[8]-48; //since last character in bankNumber string is checkDigit
//print the checkDigit
cout<<checkDigit<<endl;
  
//as per algorithm
//if subtotal%10 == checkDigit
if(subtotal[7]%10 == checkDigit){
//then print that check code is valid
cout<<"Check code is valid\n";
}
//otherwise
else{
//print check code is invalid
cout<<"Check code is invalid";
}
return 0;
}

Image of Code to better understand the indentation and comments-

OUTPUT-

Valid Bank number - 103000648

Invalid Bank number - 103000148

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