C ++拋出異常非法

Question

遇到錯誤：非法使用此類型名這是operator+重載：

    template<class T>
        inline Vec<T> Vec<T>::operator+(const Vec& rhs) const
        {
            int vecSize = 0;
            if (rhs.size() == 0 || size() == 0) {
                throw ExceptionEmptyOperand;
            }
            if (rhs.size() != size()) {
                throw ExceptionWrongDimensions;
            }
            else
            {
                Vec<T> vec;
                vecSize = rhs.size();
                for (int i = 0; i < vecSize;i++) {
                    vec.push(*this[i] + rhs[i])
            }

return vec;
        }

這是operator[]重載的聲明：

  T& operator[](unsigned int ind);
    const T& operator[](unsigned int ind) const;

第一個可以更改矢量值。

這是我嘗試做的並得到如上所述的錯誤：

template<class T>
inline T& Vec<T>::operator[](unsigned int ind) 
{
    list<T>::iterator it = vals_.begin();
    if (size() == 0) {
        throw ExceptionEmptyOperand;
    }
    if (size() < ind) {
        throw ExceptionIndexExceed;
    }


    for (unsigned int i = 0; i<ind; i++) {
            ++it;
        }
        return *it;
    }

這給了我這個錯誤：ExceptionEmptyOperand非法使用此類型作為表達式

Answer 1

如果您具有ExceptionEmptyOperand類型，則throw ExceptionEmptyOperand; 是無效的語法。 您需要創建該類型的對象，然后將其拋出：

throw ExceptionEmptyOperand();

// or
ExceptionEmptyOperand e;
throw e;

Answer 2

template<class T>
    inline Vec<T> Vec<T>::operator+(const Vec& rhs) const
    {
        int vecSize = 0;
        if (rhs.size() == 0 || size() == 0) {
            throw ExceptionEmptyOperand;
        }
        if (rhs.size() != size()) {
            throw ExceptionWrongDimensions;
        }
        Vec<T> vec;
        vecSize = rhs.size();
        for (int i = 0; i < vecSize;i++) {
            vec.push((*this)[i] + rhs[i])
        return vec;
    }


template<class T>
inline T& Vec<T>::operator[](unsigned int ind) 
{
    if (size() == 0) {
        throw ExceptionEmptyOperand;
    }
    if (size() <= ind) {
        throw ExceptionIndexExceed;
    }

    list<T>::iterator it = vals_.begin();
    for (unsigned int i = 0; i<ind; i++) {
            ++it;
    }
    return *it;
}

template<class T>
inline const T& Vec<T>::operator[](unsigned int ind) const
{
    if (size() == 0) {
        throw ExceptionEmptyOperand;
    }
    if (size() <= ind) {
        throw ExceptionIndexExceed;
    }
    list<T>::const_iterator it = vals_.begin();

    for (unsigned int i = 0; i<ind; i++) {
        ++it;
    }
    return *it;
}