To Integer Stack
by Isai Damier, Android Engineer @ Google

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/*******************************************************************
 * Author: Isai Damier
 * Title: LargeInteger.java
 * Project: geekviewpoint
 * Package: datastructure
 *
 * Description: Normally modern computers cannot handle very large
 *    numbers. So the task here is to create a datastructure that
 *    can handle numbers of perhaps infinite size. And to prove that
 *    the datastructure works, included are arithmetic operators.
 *
 *    Naturally the numbers are represented as Strings. And to
 *    perform addition and subtraction, stacks are used as the media.
 *    Finally, as any trusty calculator, this datastructure returns
 *    erroneous values for erroneous inputs and correct values for
 *    correct inputs. This is to say, if an input string does not
 *    represent a valid decimal integer, then the output string
 *    will be bogus.
 ******************************************************************/
 import java.util.Stack;
 
public class LargeInteger {
 
  private String number;
 
  public LargeInteger(String number) {
    this.number = number;
  }//constructor
 
  /***************************************************************
   * Function: toIntegerStack
   * Inputs: @param n
   * Output: Stack<Integer>
   *
   * Description: This auxiliary function converts a String into a
   *    stack of integers. The function makes no checks for erroneous
   *    values. The user will get what the user asks for.
   *
   **************************************************************/
  private Stack<Integer> toIntegerStack(String n) {
    Stack<Integer> stack = new Stack<Integer>();
    for (char c : n.toCharArray()) {
      //stack.push(c - 48);//ASCII
      stack.push(Integer.parseInt(c+""));
    }
    return stack;
  }
}