How to Create a Big Integer Class in C ?

How to Implement Big Int in C

Introduction

Working with numbers larger than the built-in data type long int requires a custom implementation called big int. Here's a general approach to designing a big int class in C .

Data Structure

Store the integer as a vector of smaller numbers, typically single digits or small base values. This allows for arbitrary length integers.

template<class BaseType>
class BigInt {
    typedef typename BaseType BT;
protected:
    std::vector<BaseType> value_;
};

Arithmetic Operations

Addition:

Implement the = operator using binary addition principles. Loop through the elements, performing addition and handling carries as needed.

template<class BaseType>
BigInt<BaseType>& BigInt<BaseType>::operator+=(BigInt<BaseType> const& operand) {
    BT count, carry = 0;
    for (count = 0; count < std::max(value_.size(), operand.value_.size()); count++) {
        //... (carry handling omitted for brevity)
    }
    return *this;
}

Other Operations (Multiplication, Division, etc.)

Other arithmetic operations leverage the implemented = and - operators. Consider using existing algorithms for optimized implementations.

Other Considerations

• Implement comparison operators (<, >, etc.) by comparing the individual elements.
• Befriend the standard input and output operators for convenient input and output.
• Ensure that the underlying BaseType is the second largest available (e.g., 32-bit int on a 64-bit system) to handle carries correctly.

The above is the detailed content of How to Create a Big Integer Class in C ?. For more information, please follow other related articles on the PHP Chinese website!