实现bigint计算器c ++

问题描述

到目前为止，我有一个add，subtract和print函数以及一个初始化为数组的构造函数。由于某种原因，操作（+和 - ）对我来说很有意义（我认为）所以我有点超越自我并且不太确定如何初始化一个大整数，我可以得到一些函数这样的帮助作为void assign（const bigint& A）或类似的东西？如果我的代码有问题，请告诉我。谢谢

So far I've got an add, subtract and print function as well as a constructor that initializes to zero the array. For some reason the operations(+ and -) made alot of sense to me(i think) so I kind of got ahead of my self and am not too sure how to initialize a big integer, could I get some help with a function such as void assign(const bigint & A) or something like that? Also if there is something already wrong with my code please tell me. Thanks

const int size=30;   //just to make things easier, will change to something big later
class bigint
{
    int digits[size];


public:
    // initializes to zero
    bigint()
    {
        for (int i = 0; i < size; i++)
            digits[i] = 0;

    }

    // prints a big int
    void print()
    {
        bigint B;
        for (int i = size - 1; i >= 0; i--)
        {
            int dig = B.digits[i];
            if (dig != 0)
                std::cout << dig;
        }
    }

    // subtracts a bigint(B) from another(A)
    void subtract(bigint & A, bigint & B)
    {
        for (int i = 0, borrow = 0; i < size; i++)
        {
            if (borrow = ((A.digits[i] -= B.digits[i] + borrow) < 0))
            {
                A.digits[i] += 10;
            }
        }
    }

    // adds a bigint(A) to another(B)
    void add(bigint & A, bigint & B)
    {
        for (int i = 0, carry = 0; i < size; i++)
        {
            if (carry = ((A.digits[i] += B.digits[i] + carry) < 9))
            {
                A.digits[i] -= 10;
            }
        }
    }
};

推荐答案

void add (const bigint& A);
void subtract (const bigint& A);

向应用操作的对象添加/减去A.



（c）以十进制数字工作不会获得最佳性能并且浪费内存。为什么不在base 2中工作，因此使用内置的算术运算。这将使您的功能性能提高一到两个数量级。只是为了打印一个数字，它需要转换回十进制。

which add/subtract A to/from the object the operation is applied to.

(c) Working in decimal digits will not get you the best performance and is a waste of memory. Why don't you work in base 2 and hence use the built-in arithmetic operations. That will increase the performance of your functions by one or two orders of magnitude. Just for the purpose of printing a number it needs to be converted back to decimal.

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