BigInt Implementation in C

This repository contains a C implementation of arbitrary-precision integers (BigInt) supporting 1024-bit unsigned integers with an additional boolean sign variable. The implementation uses base-32 representation for efficient storage, with numbers stored in an array of 32 integers.

Implementation Details

The core structure represents large integers using:

• An array of 32 integers (for base-32 storage)
• A boolean sign flag (for signed operations)
• Current implementation includes:
  • Addition
  • Subtraction
  • Multiplication

The base-32 representation was chosen to optimize storage efficiency while maintaining good computational performance.

Current Features

• Basic Arithmetic Operations:

  • addBigInt() - Adds two BigInt numbers
  • subtractBigInt() - Subtracts one BigInt from another
  • multiplyBigInt() - Multiplies two BigInt numbers

• Helper Functions:

  • Comparison functions
  • Conversion utilities
  • Memory management

Usage

Include the header file and link against the implementation:

#include "bigint.h"

int main() {
    BigInt num1 = createBigInt(...);
    BigInt num2 = createBigInt(...);
    
    BigInt sum = addBigInt(num1, num2);
    // ... other operations
    
    freeBigInt(num1);
    freeBigInt(num2);
    return 0;
}

Scope for further improvement

• The boolean sign variable, which for simplicity was implemented using the enum datatype in C, can be replaced with bitfields so that it becomes more efficient with regards to memory. Since this was a learning project, I did not implement it but it can potentially implemented.
• A more 'complete' libary can be made by introducing division functionality.

Credits

My code previously required input in hexadecimal format. The algorithm that allowed for decimal input was possible due to generous inputs from the Stack Overflow community on my question : link to my stack exchange question