用类实现高精度加法

C++ 代码

#include <iostream>
using namespace std;

class BIGINT {
public:
    int num[10000],length;

    BIGINT();
    friend istream & operator>>(istream &,BIGINT &);
    friend ostream & operator<<(ostream &,BIGINT &);
    BIGINT operator+(BIGINT);
};

BIGINT::BIGINT() {
    for(int i = 0;i < 10000;i ++) num[i] = 0;
    length = 0;
}

istream& operator>>(istream &in,BIGINT &b) {
    string s;
    in >> s;
    for(int i = s.length() - 1;i >= 0;i --)
        b.num[s.length() - 1 - i] = s[i] - '0';
    b.length = s.length();
    return in;
}

ostream& operator<<(ostream &out,BIGINT &b) {
    for(int i = b.length - 1;i >= 0;i --) out << b.num[i];
    return out;
}

BIGINT BIGINT::operator+(BIGINT b) {
    int x = max(b.length,length),add = 0;
    BIGINT c;
    for(int i = 0;i <= x;i ++) {
        c.num[i] = b.num[i] + num[i] + add;
        if(c.num[i] > 9) add = 1,c.num[i] -= 10;else add = 0;
    }
    if(c.num[x] != 0) c.length = x + 1;else c.length = x;
    return c;
}

int main() {
    BIGINT a,b,c;
    cin >> a >> b;
    c = a + b;
    cout << c;
    return 0;
}