This is a small c++ project for university.
This project is an implementation of BigInteger from Java. With this implementation, you can add, subtract, multiply, divide and compare arbitrarily big integers. Usage is presented in main.cpp as test cases. As a way of storing these integers, BigInteger uses array of decimal digits represented as int. All arithmetic operations are implemented similarly to how you would do these operation on by hand paper. One thing to note is that as you do operations on these numbers, their array size will grow, as all operations allocate enough memory to handle worst case scenarios (multiplication of two 20digit numbers will always allocate array of 40digits) and currently there's no way to shrink these arrays.
Implementation overview: All internal operations of BigInteger work with the "Array" type. They all follow these steps:
- Allocate an Array that stores the resulting number
- Perform calculations that write to the allocated array
- Return new BigInteger that takes this Array and takes the ownership of it. This way as little memory as possible is created Digits are stored in reversed order, for example 12345 is stored as [5, 4, 3, 2, 1]. This is for simplifying some algorithms, as the index of a digit is its base 10 exponent
Also dividing by 0 returns 0, because we were forbidden to throw exceptions
Usage:
#include <iostream>
#include "BigInteger.h"
int main() {
BigInteger a(133245), b(2101275), c(-927159);
BigInteger d = a*b+c;
std::cout << d.toString() << std::endl; //279983460216
return 0;
}Plans for the future (unlikely to be implemented):
- Add exception to division by 0
- Make arrays automatically smaller for numbers like '00000000000245'
- Migrate to std::array or std::vector (again, uni constraints)
- Add power operation
- Add ability to cast back to int smaller numbers
- Make operators work with built-in c++ types
- Optimize algorithms
- Add modulo operator