BigInteger

If you know Java BigInteger class, this is an implementation for it using C++.

Usage

In case you don't know it,we use this class to deal with very large numbers that can't fit in the largest dataType of numbers and cause overflow

Operations

With this class you can do many operations like :

• Unary operations
  • unary minus(-) changes the sign of its argument. A positive number becomes negative, and a negative number becomes positive.
  • prefix and postfix increment(++) It is used to increment the value of the variable by 1
  • prefix and postfix decrement(--) It is used to decrement the value of the variable by 1
• Arithmatic operations
  • Addition: The ‘+’ operator adds two operands. For example, x+y.
  • Subtraction: The ‘-‘ operator subtracts two operands. For example, x-y.
  • Multiplication: The ‘*’ operator multiplies two operands. For example, x*y.
  • Division: The ‘/’ operator divides the first operand by the second. For example, x/y.
  • Modulus: The ‘%’ operator returns the remainder when first operand is divided by the second. For example, x%y.
• Relational operations
  • ‘==’ operator checks whether the two given operands are equal or not. If so, it returns true. Otherwise it returns false. For example, 5==5 will return true.
  • ‘!=’ operator checks whether the two given operands are equal or not. If not, it returns true. Otherwise it returns false. It is the exact boolean complement of the ‘==’ operator. For example, 5!=5 will return false.
  • ‘>’ operator checks whether the first operand is greater than the second operand. If so, it returns true. Otherwise it returns false. For example, 6>5 will return true.
  • ‘<‘ operator checks whether the first operand is lesser than the second operand. If so, it returns true. Otherwise it returns false. For example, 6<5 will return false.
  • ‘>=’ operator checks whether the first operand is greater than or equal to the second operand. If so, it returns true. Otherwise it returns false. For example, 5>=5 will return true.
  • ‘<=’ operator checks whether the first operand is lesser than or equal to the second operand. If so, it returns true. Otherwise it returns false. For example, 5<=5 will also return true.

Some advantage

• You can initialize the object with a string , int or long value.
• Unlike java you don't need to type for example number1.add(number2) ,you just type number1+number2.
• Also you do all the mentioned operations if one side wasn't a BigInteger object for example

   int x=5; 
   BigInteger b="22434443535645455266366",b2; 
   b2=b+x;
  

Additional functions

• GCD : The greatest common divisor of two numbers which is the largest number that divides both of them.
  For example, the gcd of 8(2 x 4) and 12(3 x 4) is 4.
• LCM : The least number which is exactly divisible by each of the given numbers is called the least common multiple of those numbers.
  For example, consider the numbers 3, 31 and 62 (2 x 31). The LCM of these numbers would be 2 x 3 x 31 = 186.
• modPower : Given three numbers x, y and p, compute (x^y) % p.

Testing the class functions

We have created a unit testing script using python to test our class.
The script generates a very large random numbers and do some operations in python then putting generated numbers and the output in a file.
Then use the 'os' package to compile test.cpp file which take the generated numbers ,do the same operations done in python and putting the output in another file.
Finally the script compare the output of python and c++ then give the result of test which successfully passed and was identical :) .

Future work

We are going to add more functions like:

• isPrime : which check if a given numbers is prime or not
• sqrt : which return the square root of a given number
  and more useful functions. stay tuned and wait for updates ;).