用c++写一个高精度除法代码

以下是一个简单的高精度除法的C++代码示例：

#include <iostream>
#include <cstring>
#include <cstdio>
using namespace std;

const int MAXN = 10010; // 数组的最大长度
const int BASE = 10; // 进制

struct BigInt {
    int len, s[MAXN];

    BigInt() {
        memset(s, 0, sizeof(s));
        len = 1;
    }

    BigInt(int num) {
        *this = num;
    }

    BigInt(const char* num) {
        *this = num;
    }

    BigInt operator = (int num) {
        char s[MAXN];
        sprintf(s, "%d", num);
        *this = s;
        return *this;
    }

    BigInt operator = (const char* num) {
        memset(s, 0, sizeof(s));
        len = strlen(num);
        for (int i = 0; i < len; i++) s[i] = num[len - 1 - i] - '0';
        return *this;
    }

    string str() const {
        string res = "";
        for (int i = 0; i < len; i++) res = (char)(s[i] + '0') + res;
        if (res == "") res = "0";
        return res;
    }

    BigInt operator + (const BigInt& b) const {
        BigInt c;
        c.len = 0;
        for (int i = 0, g = 0; g || i < max(len, b.len); i++) {
            int x = g;
            if (i < len) x += s[i];
            if (i < b.len) x += b.s[i];
            c.s[c.len++] = x % BASE;
            g = x / BASE;
        }
        return c;
    }

    BigInt operator - (const BigInt& b) const {
        BigInt c;
        c.len = 0;
        for (int i = 0, g = 0; i < len; i++) {
            int x = s[i] - g;
            if (i < b.len) x -= b.s[i];
            if (x >= 0) g = 0;
            else {
                g = 1;
                x += BASE;
            }
            c.s[c.len++] = x;
        }
        c.trim();
        return c;
    }

    BigInt operator * (const BigInt& b) const {
        BigInt c;
        c.len = len + b.len;
        for (int i = 0; i < len; i++)
            for (int j = 0; j < b.len; j++)
                c.s[i + j] += s[i] * b.s[j];
        for (int i = 0; i < c.len - 1; i++) {
            c.s[i + 1] += c.s[i] / BASE;
            c.s[i] %= BASE;
        }
        c.trim();
        return c;
    }

    // 高精度除法
    BigInt operator / (const BigInt& b) const {
        BigInt c;
        c.len = len - b.len + 1;
        for (int i = c.len - 1; i >= 0; i--) {
            BigInt t = b;
            if (*this < t * BigInt(BASE) * BigInt(i)) {
                c.s[i] = 0;
                continue;
            }
            int l = 0, r = BASE - 1, ans;
            while (l <= r) {
                int mid = (l + r) >> 1;
                if (*this >= t * BigInt(mid)) {
                    ans = mid;
                    l = mid + 1;
                } else r = mid - 1;
            }
            c.s[i] = ans;
            *this = *this - t * BigInt(ans);
        }
        c.trim();
        return c;
    }

    // 去掉前导0
    void trim() {
        while (len > 1 && !s[len - 1]) len--;
    }

    // 判断大小
    bool operator < (const BigInt& b) const {
        if (len != b.len) return len < b.len;
        for (int i = len - 1; i >= 0; i--)
            if (s[i] != b.s[i]) return s[i] < b.s[i];
        return false;
    }

    bool operator > (const BigInt& b) const {
        return b < *this;
    }

    bool operator <= (const BigInt& b) const {
        return !(b < *this);
    }

    bool operator >= (const BigInt& b) const {
        return !(*this < b);
    }

    bool operator != (const BigInt& b) const {
        return b < *this || *this < b;
    }

    bool operator == (const BigInt& b) const {
        return !(b < *this) && !(*this < b);
    }
};

ostream& operator << (ostream& out, const BigInt& x) {
    out << x.str();
    return out;
}

istream& operator >> (istream& in, BigInt& x) {
    string s;
    in >> s;
    x = s.c_str();
    return in;
}

int main() {
    BigInt a, b, c;
    cin >> a >> b;
    c = a / b;
    cout << c << endl;
    return 0;
}

该代码中定义了一个结构体`BigInt`，表示高精度整数。实现了加法、减法、乘法和除法操作。其中，高精度除法的实现是用二分法来找出商的每一位。

使用时只需要输入两个字符串，分别表示被除数和除数，然后调用`/`操作符即可得到商。