C++大作业，重载函数时出问题，好像不能调用普通函数，有无大神指导

Question

#include <iostream>
#include <string>
#include <cmath>
#include<algorithm>
using namespace std;

class VeryLongInt{
protected:
    string a;
public:
    VeryLongInt(){}
    VeryLongInt(string x){
        a.assign(x);
    }
    ~VeryLongInt(){}
    VeryLongInt operator + (const VeryLongInt &b);
    VeryLongInt operator - (const VeryLongInt &b);
    VeryLongInt operator * (const VeryLongInt &b);
    VeryLongInt operator / (const VeryLongInt &b);
    void display(){
        cout << a <<endl;
    }
    int copy(int *a,int *b){
        int i,j;
        for(i = 0;i < 1000;i++)
            a[i] = 0;
        for(i = 999;b[i]==0;i--);
        for(j = 0;j <= i;j++)
            a[i] = b[i];
        return i+1;
    }
    int compare(int *a,int *b){
        int i,j;
        for(i = 999;a[i] == 0;i--);
        for(j = 999;b[j] == 0;j--);
        if (i < j)
            return -1;
        else if(i > j)
            return 1;
        else {
            for(;i >= 0;i--){
                if (a[i] > b[i])
                    return 1;
                else if(a[i] < b[i])
                    return -1;
            }
            return 0;
        }
    }
};

VeryLongInt VeryLongInt ::operator + (const VeryLongInt &b) {
    VeryLongInt B;
    int carry = 0;
    string s1 = this->a;
    string s2 = b.a;
    int len1 = s1.size();
    int len2 = s2.size();
    int lenLong;
    int lenShort;
    if(len1 <= len2) {
        lenLong = len2;
        lenShort = len1;
    }
    else {
        lenLong = len1;
        lenShort = len2;
    }
    string s3(lenLong + 1,'0');
    for(int i = 0;i <= lenShort;i ++) {
        if ((s1[len1 - i] - '0') + (s2[len2 - i] - '0') + carry <= 9) {
            s3[lenLong + 1 - i] = (s1[len1 - i] - '0' + s2[len2 - i] + carry);
            carry = 0;
        } else {
            s3[lenLong + 1 - i] = (s1[len1 - i] - '0' + s2[len2 - i] - 10 + carry);
            carry = 1;
        }
    }
    if(len1 > len2){
        for(int i = lenShort + 1;i <= lenLong ;i ++){
            if(s1[len1-i] - '0' + carry <= 9){
                s3[lenLong + 1 - i] = s1[len1-i] + carry;
                carry = 0;
            }
            else{
                s3[lenLong + 1 - i] = s1[len1-i] + carry - 10;
                carry = 1;
            }
        }
        if(carry == 1)
            s3[0] = '1';
        else
            s3[0] = '0';
    }
    else if( len1 <len2 ){
        for(int i = lenShort + 1;i <= lenLong ;i ++){
            if(s2[len2-i] - '0' + carry <= 9){
                s3[lenLong + 1 - i] = s2[len2-i] + carry;
                carry = 0;
            }
            else{
                s3[lenLong + 1 - i] = s2[len2-i] + carry - 10;
                carry = 1;
            }
        }
        if(carry == 1)
            s3[0] = '1';
        else
            s3[0] = '0';
    }
    B.a.assign(s3);
    return B;
}

VeryLongInt VeryLongInt ::operator - (const VeryLongInt &b){
    VeryLongInt B;
    int carry = 0;
    string s1 = this->a;
    string s2 = b.a;
    int len1 = s1.size();
    int len2 = s2.size();
    int lenLong;
    int lenShort;
    if(len1 <= len2){
        lenLong = len2;
        lenShort = len1;
    }
    else {
        lenLong = len1; lenShort = len2;
    }
    string s3(lenLong + 1,'0');
    if( len1 == len2) {
        int bigger = 1;
        for (int i = 0; i <= len1; i++) {
            if (s1[i] < s2[i]) {
                bigger = 0;
                break;
            }
        }
        if (bigger) {
            for (int i = 0; i <= len1; i++) {
                if ((s1[len1 - i] - '0') - (s2[len2 - i] - '0') + carry >= 0) {
                    s3[lenLong + 1 - i] = (s1[len1 - i] + '0' - s2[len2 - i] + carry);
                    carry = 0;
                } else {
                    s3[lenLong + 1 - i] = (s1[len1 - i] + '0' - s2[len2 - i] + 10 + carry);
                    carry = -1;
                }
            }
        } else {
            for (int i = 0; i <= len1; i++) {
                if ((s2[len1 - i] - '0') - (s1[len2 - i] - '0') + carry >= 0) {
                    s3[lenLong + 1 - i] = (s2[len1 - i] + '0' - s1[len2 - i] + carry);
                    carry = 0;
                } else {
                    s3[lenLong + 1 - i] = (s2[len1 - i] + '0' - s1[len2 - i] + 10 + carry);
                    carry = -1;
                }
            }
            s3[0] = '-';
        }
    }
    else if(len1 > len2){
        for(int i = 0;i <= lenShort;i ++){
            if((s1[len1-i] - '0') - (s2[len2-i] - '0') + carry >= 0){
                s3[lenLong + 1 - i] = (s1[len1-i] + '0' - s2[len2-i] + carry);
                carry = 0;
            }
            else {
                s3[lenLong + 1 - i] = (s1[len1-i] + '0' - s2[len2-i] + 10 + carry);
                carry = -1;
            }
        }
        for(int i = lenShort + 1;i <= lenLong ;i ++){
            if(s1[len1-i] - '0' + carry >= 0){
                s3[lenLong + 1 - i] = s1[len1-i] + carry;
                carry = 0;
            }
            else{
                s3[lenLong + 1 - i] = s1[len1-i] + carry + 10;
                carry = -1;
            }
        }
    }
    else if(len2 > len1){
        for(int i = 0;i <= lenShort;i ++){
            if((s2[len2-i] - '0') - (s1[len1-i] - '0') + carry >= 0){
                s3[lenLong + 1 - i] = (s2[len2-i] + '0' - s1[len1-i] + carry);
                carry = 0;
            }
            else {
                s3[lenLong + 1 - i] = (s2[len2-i] + '0' - s1[len1-i] + 10 + carry);
                carry = -1;
            }
        }
        for(int i = lenShort + 1;i <= lenLong ;i ++){
            if(s2[len2-i] - '0' + carry >= 0){
                s3[lenLong + 1 - i] = s2[len2-i] + carry;
                carry = 0;
            }
            else{
                s3[lenLong + 1 - i] = s2[len2-i] + carry + 10;
                carry = -1;
            }
        }
        s3[0] = '-';
    }
    B.a.assign(s3);
    return B;
}


VeryLongInt VeryLongInt ::operator * (const VeryLongInt &b){
    VeryLongInt B;

    int u[1000];
    for(int i = 0;i < 1000;i++){
        u[i] = 0; }
    int v[1000];
    for(int i = 0;i < 1000;i++){
        v[i] = 0; }
    int w[1000];
    for(int i = 0;i < 1000;i++){
        w[i] = 0; }

    string str1 = this->a;
    string str2 = b.a;
    int i,j,k,carry = 0,tmp;
    int len1 = str1.size();
    int len2 = str2.size();
    for(i = 0;i < len1;i++){
        u[i] = str1[len1 - 1 - i] - '0';
    }
    for(i = 0;i < len2;i++){
        v[i] = str2[len2 - 1 - i] - '0';
    }

    for(i = 0;i < len1;i++){
        for(k = i,j = 0;j < len2;j++,k++){
            w[k] += u[i] * v[j]; }
    }
    for(i = 0;i <= k;i++){
        w[i] += carry;
        tmp = w[i];
        w[i] = tmp % 10;
        carry = tmp/10;
    }

    for(i = k;w[i] == 0;i--);
    for(;i >= 0;i--)
        cout << w[i] ;
    cout <<endl;

    return B;
}

VeryLongInt VeryLongInt ::operator / (const VeryLongInt &b){
    VeryLongInt B;
    int u[1000];
    for(int i = 0;i < 1000;i++){
        u[i] = 0;
    }
    int v[1000];
    for(int i = 0;i < 1000;i++){
        v[i] = 0;
    }
    int w[1000];
    for(int i = 0;i < 1000;i++){
        w[i] = 0;
    }
    int i,j,tmp1,tmp2 = 0,borrow = 0;
    int temp1[1000] = {0};
    int temp2[1000] = {0};
    string str1 = this->a;
    string str2 = b.a;
    int len1 = str1.size();
    int len2 = str2.size();
    for(i = 0;i < len1;i++)
        u[i] = str1[len1 - 1 -i] - '0';
    for(i = 0;i < len2;i++)
        v[i] = str2[len2 - 1 -i] - '0';

    if(compare(u,v) < 0){
        cout << endl;
        return B;
    }
    while(compare(u,v) >= 0){
        tmp1 = len1 - len2;
        if (tmp1 == tmp2&&tmp1 > 0)
            tmp1--;
        tmp2 = tmp1;
        for(int i = 0;i < 1000;i++){
            temp2[i] = 0;
        }
        for (i = len1 - 1; i >= tmp1; i--) {
            temp2[i] = v[i - tmp1];
        }
        copy(temp1,u);

        if(compare(temp1,temp2) < 0)
            continue;
        for (j = 1;;j++) {
            borrow = 0;
            for(i = tmp1;i < len1;i++) {
                temp1[i] = u[i] - temp2[i] - borrow;
                if(temp1[i] < 0){
                    borrow = 1;
                    temp1[i] += 10;
                }
                else
                    borrow = 0;
            }
            len1 = copy(u,temp1);
            w[tmp1] = j;
            if (compare(temp1,temp2) < 0)
                break;
        }
    }
    for(i = 999;w[i] == 0;i --);
    for(;i >= 0;i--)
        cout << w[i];
    cout << endl;
}


int main(){
    //string x;
    //string y;
    //cin >> x;
    VeryLongInt A("666");
    VeryLongInt B("111");
    VeryLongInt result = A / B;
    //result.display();
}

运行环境为clion，有无大神指出问题在哪

Answer 1

你确定下的copy函数执行效果是不是和你想的一样？u是666，你执行完之后复制了一个6.，以至于你下面的那句if(compare)一直都不会满足。还有，我不建议你每个数组都开辟1000，这么做会让你判断数组的长度出现很大的问题，以至于你就算只有一个数，也要遍历1000次，双重遍历就是1000*1000，这会造成很多的问题。所以应该换成动态数组，或者使用指针来代替。