添加 HugeInteger 字符串对象

Question

我正在解决一个问题，我必须添加将数字存储在字符串对象中的 HugeInteger 对象。当我运行程序并输入 2 个值（即 100000000000000000000000000000000000000000000000000000 1）时，我得到一个 Debug Assertion Failed...Expression: string subscript out or range 消息。我认为问题是由于我的 operator += 函数造成的。不确定如何实现进位部分/添加字符串。将不胜感激有关如何解决此问题的一些想法。

这是我的代码。

HugeInteger.h

#include <iostream>
#include <array>
#include <string>

class HugeInteger
{
    // need to offer friendship to these 2 functions
    friend std::istream & operator >> (std::istream & src, HugeInteger & value);
    friend std::ostream & operator << (std::ostream & dest, const HugeInteger & value);

public:
    //ctor that converts a "long long" into a HugeInteger
    HugeInteger(long long value = 0LL); //0LL is constant literal value 0
    //   of type long long

    //ctor that converts a string into a HugeInteger
    HugeInteger(const char *str);

    //Convert a string into a HugeInteger
    void input(const std::string& str);

    //adds RHS into LHS (the object pointed to by the "this" pointer) and returns result
    HugeInteger & operator +=(const HugeInteger & RHS);

    //adds a "long long" (RHS) and LHS and puts result into a temp HugeInteger
    //   and returns result
    HugeInteger operator +(long long RHS) const;

    //adds a string (which will be converted into a HugeInteger) with LHS into a temp 
    //       HugeInteger and returns result
    HugeInteger operator +(const char * RHS) const;

    // overload preincrement operator for the HugeInteger class
    HugeInteger & operator ++ (void);

private:
    bool negative;  // will be true if number is negative
    std::string hugeInt; // each digit is stored in a string object
};

//overloads the << and >> operators for the HugeInteger class
std::istream & operator >> (std::istream & src, HugeInteger & value);
std::ostream & operator << (std::ostream & dest, const HugeInteger & value);

HugeInteger.cpp

#include "HugeInteger.h"
#include <sstream>

#include <iostream>
using namespace std;

HugeInteger::HugeInteger(long long value)
{
    // set all MaxDigit digits to zero to start
    this->negative = false;
    if (value < 0LL){ // 0LL is constant literal 0 of type long long
        this->negative = true;
        value = -value; // make the value positive                  
    }

    unsigned int i = 0;


        for (; i < hugeInt.size(); i++)
        {
            this->hugeInt[i] = '0';
        }
        this->hugeInt[i] = '\0';



    // convert individual digits of input value into a HugeInteger
    for (unsigned int j = hugeInt.size() - 1; j >= 0 && value != 0LL; j--)
    {
        short result = value % 10;
        char c = (char)result;
        this->hugeInt[j] = c;
        value /= 10;
    }

    // test to make sure that HugeInteger was able to contain value

    if (value != 0LL){
        *this = 0LL; // set to -0, to signal overflow
        this->negative = true; //   Possibly should increase value assigned
    }                          //   to MaxDigit to fix this problem.
}

// converts string into a HugeInteger object
HugeInteger::HugeInteger(const char *str)
{
    this->input(str);
}

// converts long long into HugeInteger and then invokes
//    HugeInteger::operator +=(const HugeInteger & )
HugeInteger HugeInteger::operator +(long long value) const
{
    HugeInteger temp = *this;
    return temp += (HugeInteger(value));
}


//converts string into HugeInteger and then invokes
 //   HugeInteger::operator +=(const HugeInteger & )
HugeInteger HugeInteger::operator +(const char *str) const
{
    HugeInteger temp = *this;
    return temp += (HugeInteger(str));
}

// Adds into the HugeInteger pointed to by the "this" pointer 
//   the HugeInteger op.
//   Then the calculated result is returned
HugeInteger & HugeInteger::operator+=(const HugeInteger &op)
{


    int carry = 0;

    for (int i = op.hugeInt.size() - 1; i >= 0; i--)
    {
        this->operator++();
        int temp = this->hugeInt[i];
        temp += carry;

        this->hugeInt[i] = char(temp);
        if (int(this->hugeInt[i]) > 9)
        {
            int temp = int(this->hugeInt[i]);
            temp -= 10;
            this->hugeInt[i] = char(temp);
            carry = 1;
        }

        else
        {
            carry = 0;
        }

    }

    return *this;
}

void HugeInteger::input(const std::string& str)
{
    // assume positive for now
    this->negative = false;

    // init. to all zeros first
    unsigned int i = 0;

    this->hugeInt.clear();

    while (i < str.size())
    {
        if (isdigit(str[i]))
            this->hugeInt += str[i];
        i++;
    }
}

// Pre-increment operator
HugeInteger & HugeInteger::operator ++ ()
{
    string key = this->hugeInt;

    istringstream in(key);
    int int_key;
    in >> int_key;
    int_key++;
    ostringstream out;
    out << int_key;
    key = out.str();
    this->hugeInt = key;

    return *this;
}

istream & operator>>(istream & input, HugeInteger & value)
{
    string inputString;
    input >> inputString;
    value.input(inputString);
    return input;
}

ostream & operator << (ostream & output, const HugeInteger & value)
{
    // find first non-zero digit
    unsigned int i = 0;

    if (value.hugeInt.size() == 0)
    {
        cout << '0';
    }

    while (i < value.hugeInt.size()){
        if (value.hugeInt[i] != '0'){
            break;
        }
        ++i;
    }

    // if all zeros, just output a single 0
    if (i == 40)
    {
        cout << '0';
        return output;
    }

    // check if we need to ouput a negative sign
    if (value.negative){
        cout << '-';
    }

    // output remaining digits
    for (; i < value.hugeInt.size(); i++)
    {
        cout << value.hugeInt[i];
    }

    return output;
}

主程序

#include "HugeInteger.h" // include definiton of class HugeInteger
using namespace std;

int main()
{
    HugeInteger A, B, C, D;

    // input value for A & B
    cout << "****** Test << & >> operators ******\n\n";
    cout << "Input values for A and B: ";
    cin >> A >> B;
    cout << "\nA = " << A << "\nB = " << B;

    D = B;

    // test += operator
    cout << "\n\n****** Test += operator ******\n\n";
    cout << "A = " << A << "\nB = " << B << "\nC = " << C << "\n\n";
    cout << "C = B += A\n";
    C = B += A;
    cout << "\nA = " << A << "\nB = " << B << "\nC = " << C;
    B = D;  // restore B's value

    system("pause");
    return 0;
} // end main

Answer 1

在HugeInteger::operator+=()，

for (int i = op.hugeInt.size() - 1; i >= 0; i--)
{
    this->operator++();
    int temp = this->hugeInt[i];

i 以op.hugeInt.size() - 1 为界，但它可能超出this->hugeInt 的范围，因为this->hugeInt 可能要短得多。