Giganum

Giganum is a C library allowing for arithmetic operations on integers of an arbitrary size, unconstrained by the size limitations of standard number types.

Right now the only implemented functions are addition and subtraction, and only positive numbers are supported, but more functions are coming soon!

Building

In your shell, do the following:

git clone https://github.com/calebstein1/giganum
cd giganum
make

This will build libgiganum, place it in the lib directory, and run the tests in the 'test' directory.

Usage

To use libgiganum in your program, you'll need to include giganum.h which can be found in the include directory, and you'll link against libgiganum.so. Do note that a giganum cannot interact directly with regular number types, so you'll have to create a new giganum for each number that needs to be a part of your operation, even if that number could be represented by a standard number type.

Functions

giga_init

In your code, you can create a new giganum using giga_init:

giganum_t* my_giganum = giga_init("123456789123456789123456789");

The giga_init function takes a char* of digits and returns a pointer to a giganum_t, or NULL if something went wrong. The giganum_t pointed to by the return value of giga_init is dynamically allocated by the function, and so it is your responsibility to free it when you're finished with it.

giga_print

The giga_print function takes a pointer to a giganum_t and simply prints the string representation of the value of the passed in giganum_t pointer.

giganum_t* my_giganum = giga_init("12345678901234567890");
giga_print(my_giganum);

giga_add

The giga_add function takes two giganum_t pointers, adds the values, and returns a pointer to a new giganum_t containing the summed value. Remember that all of these pointers will need to be freed separately.

giganum_t* my_giganum1 = giga_init("123456789");
giganum_t* my_giganum2 = giga_init("9876543210");
giganum_t* sum_result = giga_add(my_giganum1, my_giganum2);

giga_subtract

The giga_subtract function takes two giganum_t pointers, subtracts the second from the first, and returns a pointer to a new giganum_t containing the difference. The value of the second giganum_t but be less than or equal to the value of the first. Because negative values are not supported by libgiganum at all, having the second value larger than the first is considered undefined behavior. Don't do it. And as always, remember to free your pointers.

giganum_t* my_giganum1 = giga_init("9876543210");
giganum_t* my_giganum2 = giga_init("123456789");
giganum_t* sum_result = giga_subtract(my_giganum1, my_giganum2);