How to resolve the algorithm Luhn test of credit card numbers step by step in the XPL0 programming language

Published on 12 May 2024 09:40 PM
#Xpl0

How to resolve the algorithm Luhn test of credit card numbers step by step in the XPL0 programming language

Table of Contents

Problem Statement

The Luhn test is used by some credit card companies to distinguish valid credit card numbers from what could be a random selection of digits. Those companies using credit card numbers that can be validated by the Luhn test have numbers that pass the following test:

For example, if the trial number is 49927398716:

Write a function/method/procedure/subroutine that will validate a number with the Luhn test, and use it to validate the following numbers:

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Luhn test of credit card numbers step by step in the XPL0 programming language

Source code in the xpl0 programming language

string 0;               \use zero-terminated strings

func    Valid(Str);     \Return 'true' if digits in Str pass Luhn test
char    Str;
int     Len, Sum, I, Dig;
[Len:= 0;               \find length of Str
while Str(Len) do Len:= Len+1;
Sum:= 0;                \sum even and odd digits
for I:= 0 to Len-1 do   \(no need to reverse)
        [if (I xor Len) and 1 then
                Sum:= Sum + Str(I) - ^0
        else    [Dig:= Str(I) - ^0;
                Dig:= Dig*2;
                Sum:= Sum + Dig/10 + rem(0);
                ];
        ];
return rem(Sum/10) = 0; 
];

int     Luhn, N;
[Luhn:= ["49927398716",
         "49927398717",
         "1234567812345678",
         "1234567812345670"];
for N:= 0 to 4-1 do
        [Text(0, Luhn(N));
         Text(0, if Valid(Luhn(N))
                then " is valid"
                else " is not valid");
        CrLf(0);
        ];
]

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