This repository implements a big integer library in C. The library supports many operations, such as basic arithmetic, comparison, fast modular exponentiation, prime number detection, square roots, and more.
To use the library, first include it in your C file.
#include "bigint.h"To create a new big integer, use the bigint struct. You can initialize a big integer from a string, an integer, or another big integer.
int main() {
// Initialize a big integer from a string
bigint a = bigint_from_string("123456789012345678901234567890");
// Initialize a big integer from an integer
bigint b = bigint_from_int(1234567890);
// Initialize a big integer from another big integer
bigint c = bigint_copy(a);
bigint_delete(a);
bigint_delete(b);
bigint_delete(c);
return 0;
}To perform arithmetic operations on big integers, use the provided functions.
int main() {
// Initialize big integers
bigint a = bigint_from_string("123456789012345678901234567890");
bigint b = bigint_from_string("987654321098765432109876543210");
// Perform arithmetic operations
bigint c = bigint_add(a, b);
bigint d = bigint_sub(a, b);
bigint e = bigint_mul(a, b);
bigint f = bigint_div(a, b);
bigint g = bigint_mod(a, b);
bigint_delete(a);
bigint_delete(b);
bigint_delete(c);
bigint_delete(d);
bigint_delete(e);
bigint_delete(f);
bigint_delete(g);
return 0;
}To compare big integers:
int main() {
// Initialize big integers
bigint a = bigint_from_string("123456789012345678901234567890");
bigint b = bigint_from_string("987654321098765432109876543210");
// Compare big integers
if (bigint_eq(a, b)) {
printf("a == b\n");
} else if (bigint_lt(a, b)) {
printf("a < b\n");
} else if (bigint_gt(a, b)) {
printf("a > b\n");
}
bigint_delete(a);
bigint_delete(b);
return 0;
}To perform fast modular exponentiation:
int main() {
// Initialize big integers
bigint a = bigint_from_string("2");
bigint b = bigint_from_string("1234");
bigint m = bigint_from_string("10007");
// Perform fast modular exponentiation
bigint c = bigint_fast_pow(a, b, m);
bigint_delete(a);
bigint_delete(b);
bigint_delete(c);
bigint_delete(m);
return 0;
}To check if a big integer is prime:
int main() {
// Initialize a big integer
bigint a = bigint_from_string("123456789012345678901234567890");
// Check if the big integer is prime
if (bigint_is_prime(a)) {
printf("a is prime\n");
} else {
printf("a is not prime\n");
}
bigint_delete(a);
return 0;
}To calculate the square root of a big integer:
int main() {
// Initialize a big integer
bigint a = bigint_from_string("123412341");
// Calculate the square root
bigint b = bigint_sqrt(a);
bigint_delete(a);
bigint_delete(b);
return 0;
}To build your program with the big integer library, simply add it to your include path and link against the C standard library.
gcc -I path/to/bigint main.c -o mainTo build with CMake, you can use a CMakeLists.txt file like the following:
cmake_minimum_required(VERSION 3.0)
# Create a new project
project(HelloWorld)
# Add an executable
add_executable(HelloWorld main.c)
include_directories(path/to/bigint)Alternatively, you can use FetchContent to download the big integer repository and include it in your project.
# Import the library from the git repo
include(FetchContent)
FetchContent_Declare(
bigint
GIT_REPOSITORY https://github.com/adam-mcdaniel/bigint
GIT_TAG main
)
FetchContent_MakeAvailable(bigint)
# Include the header only library
include_directories(${bigint_SOURCE_DIR})This project is licensed under the MIT License - see the LICENSE file for details.