arrays in pseudocode

Avuya Mxoli

Im still working on the ISBN project and now Ive validated it, the next step is to convert a 10-digit ISBN to a 13-digit ISBN. I got the formular for that now I want to create procedural pseudocode showing the steps. I was thinking of using an array to store the 10 digit array because inorder to convert it I have to divide the digits somehow coz the formular wants us to add the digits in the even positions then multiply them by 3, add that to the sum of the digits in the odd positions...and so on. So if this was a normal c# problem I'd store the ISBN in a file each digit seperated by a character e.g 0#2#3#0#4#5#6#4#7#9 so that I can use a streamreader to store the odd numbers alone and the even numbers alone in seperate arrays... I'll stop here for now in case thers things that aren't clear. Thanks

9 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes15y ago
Accepted answer
Actually, I think we both said it :)

However, to write a string to a file you can do:

System.IO.File.WriteAllText(filePath, myString);

or, if you're working from a char array, you need this step first:

string myString = new string(myCharArray);

No delimiters have been added in either case.
Avuya Mxoli15y ago
again Sam I'm sorry and I want pseudocode but now that you say the syntax dznt matter then I'll do it myself. I just wanted an idea though, Thnx anyway
Avuya Mxoli15y ago
thanks Vulpes
Sam Hobbs15y ago
Remember that the title says pseudocode? Is that incorrect or are you asking for pseudocode? Note that pseudocode can have whatever syntax you want; what is correct for one person is incorrect for someone else. If you don't want pseudocode then say so and also in the future please think about what you are using for the subject. The subject should be used to help others to decide whether they might be able to help, and the subject can help others in the future to find solutions. You seem to want to know how to read numbers (ISBNs) from a file but the subject "arrays in pseudocode" would not help someone find this thread if they wanted the solution.

So do you want help with real code (not pseudocode) for reading ISBNs?
Avuya Mxoli15y ago
hello sam, remember u sed i can write to a file without using delimiters? can u plz show me how coz im finding it difficult to write the user input(isbn) to an array and seperate it with a # before i can write to a file. So i guess I dont need the character anymore. Thanx
Vulpes15y ago
I'm not too good with pseudo-code as I tend to think in C-family language terms.

However, here's my attempt:

STORE 10-digit ISBN string in a file with consecutive digits separated by #'s
READ ISBN string from file
SPLIT ISBN string into individual digit strings
STORE the 10 digit strings in an 'items' array
DECLARE 'evenTotal' to hold total of digits in even positions
DECLARE 'oddTotal' to hold total of digits in odd positions

FOR index = 1 TO 10

   item = items[index]
   CONVERT item string to integer
   STORE integer in 'digit'
   IF one less than index divides exactly by 2
   ADD digit to evenTotal
   ELSE
   ADD digit to oddTotal

NEXT index

MULTIPLY evenTotal by 3 and add it to oddTotal
STORE in 'result'
DIVIDE result by 10 and restore in result
SUBTRACT result from 10
STORE in 'remainder'
Avuya Mxoli15y ago
thanks Vulpes I tried it and it works. Here is the rest of the formular though, after you get the "result" in ur code then divide it by 10 and subtract the remainder of the answer from 10. Which in this example leaves 2. Now plz show me the pseudocode part of the problem coz I really dnt knw the array syntax. Thanks
Sam Hobbs15y ago
Note that you can access each character of a string in the same manner as an array. So unless I misunderstand something you don't need to use a delimiter; just read the 10 digits as a string and then convert each digit to a number. You could probably read each digit separately one digit at a time (into an "int" or similar data type directly) using a format but it is more reliable to just read the string and then check to ensure that it is 10 characters, or whatever is relevant, before processing further.

Okay, sorry Vulpes; I now see your note that the bottom of your post says what I said.
Vulpes15y ago
I'm not quite sure what you're asking for here but, before trying to express this procedure in pseudocode, I'd advise you to code it and test it in an actual programming language such as C# first so that you know that the algorithm works and that you haven't omitted any steps.

If you have a text file containing the line: 0#2#3#0#4#5#6#4#7#9, then you could read it and parse it as follows:

using System;
using System.IO;

class Test
{
   static void Main()
   {
   string isbn = File.ReadAllText("isbn.txt"); // uses StreamReader behind the scenes
   string[] items = isbn.Split('#');
   int evenTotal = 0;
   int oddTotal = 0;

   for(int i = 1; i <= items.Length; i++)
   {
   int digit = int.Parse(items[i-1]);
   if (i % 2 == 0) //even position
   evenTotal += digit;
   else // odd position
   oddTotal += digit;
   }

   int result = 3 * evenTotal + oddTotal;
   Console.WriteLine(result); // 3 * 20 + 20 = 80
   Console.ReadKey();
   }
}

Incidentally, there's no real need for the # separators in the file. You could still do it by iterating through the characters in the string and converting them to digits - the code would need adjusting a bit.