Applications (Abstract Data Type (ADT) Part 5.1
Posted by JanWan
Last Updated: April 07, 2012


Stack of books

Stacks have numerous applications. We see stacks in everyday life, from the books in our library, to the sheaf of papers that we keep in our printer tray. All of them follow the Last In First Out(LIFO) logic, that is when we add a book to a pile of books, we add it to the top of the pile, whereas when we remove a book from the pile, we generally remove it from the top of the pile.

Given below are a few applications of stacks in the world of computers:


Converting a decimal number into a binary number

Decimal to binary conversion of 23

The logic for transforming a decimal number into a binary number is as follows:

1.     Read a number

2.     Iteration (while number is greater than zero)

1.     Find out the remainder after dividing the number by 2

2.     Print the remainder

3.     Divide the number by 2

3.     End the iteration

However, there is a problem with this logic. Suppose the number, whose binary form we want to find is 23. Using this logic, we get the result as 11101, instead of getting 10111.

To solve this problem, we use a stack. We make use of the LIFO property of the stack. Initially we push the binary digit formed into the stack, instead of printing it directly. After the entire digit has been converted into the binary form, we pop one digit at a time from the stack and print it. Therefore we get the decimal number is converted into its proper binary form.


function outputInBinary(Integer n)

    Stack s = new Stack

    while n > 0 do

        Integer bit = n modulo 2


        if s is full then

            return error

        end if

        n = floor(n / 2)

    end while

    while s is not empty do


    end while

end function


Notes continue into the next blog:
Applications part 5 Continue (Abstract Data Type (ADT)) 



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