c++ - 运算符重载实现 : 0xC0000005: Access violation reading location

Question

当 return BigInt(*this) += other; 在我的 BigInt 实现中执行时，出现错误 0xC0000005: Access violation reading location (insert memory location here) out 并且程序关闭。对它为什么这样做有帮助吗？有关我程序的先前上下文，请转到 Copy Constructor Issue C++: "0xC0000005: Access violation writing location 0x00000000."

BigInt.cpp

// binary addition
BigInt BigInt::operator+(BigInt const& other) const {

    return BigInt(*this) += other;

}

// compound addition-assignment operator
BigInt BigInt::operator+=(BigInt const& other) {
    //return this->data = this->data + other.data;

    //BigInt thisBigInt = *this;

    if (!other.isPositive) {
        //return thisBigInt -= other;
    }
    //possible check for both negative???


    int sum = 0; //holds the sum of the value in both vectors
    int maxSize = 0; //holds size of biggest BigInt
    int carry = 0; //holds carry over value
    int sizeDifference = 0; //holds size difference between b and a if b is bigger

    //check size
    while (bigIntVector->getSize() < other.bigIntVector->getSize()) {
        bigIntVector->resize(); //increase size of first big int until it matches size of second
    }

    if (bigIntVector->getSize() > other.bigIntVector->getSize()) {
        sizeDifference = bigIntVector->getSize() - other.bigIntVector->getSize();
        //cout << "sizeDiff: " << sizeDifference << endl;
    }

    maxSize = bigIntVector->getSize();

    int otherCounter = other.bigIntVector->getSize() - 1; //keeps track if we are done getting digits from other array
    //cout << "otherCounter: " << otherCounter << endl;

    for (int i = maxSize - 1; i >= 0; i--) {
        //cout << "element1: " << bigIntVector.getElementAt(i) << endl;
        //cout << "element2: " << other.bigIntVector.getElementAt(i) << endl;
        sum += bigIntVector->getElementAt(i);
        if (otherCounter >= 0) {
            sum += other.bigIntVector->getElementAt(i - sizeDifference); //move index if size is different
            sum += carry;
            carry = 0;
            //cout << "sum: " << sum << endl;
            if (sum > 9) {
                ++carry;
                bigIntVector->setElementAt(i, sum%base);
            }
            else {
                carry = 0;
                bigIntVector->setElementAt(i, sum%base);
            }

            --otherCounter; //only decrement otherCounter if we have reached 2nd vector elements
        }
        if (otherCounter < 0 && carry > 0) {
            bigIntVector->resize(); //increase size of big int
            bigIntVector->setElementAt(i, carry); //set carry in front of sum spot
        }
        sum = 0;
    }

    return *this;

}

Answer 1

您正在从 operator+= 按值返回 BigInt，这会创建一个拷贝，并且您可能没有指定一个正确的复制构造函数来处理或内部动态分配的内存，你应该返回一个引用:

BigInt& BigInt::operator+=(BigInt const& other)