Question

I’m learning boost and I wanted to rewrite my Matrix class. Instead of for loops I wanted to use BOOST_FOREACH, however I have some problems with operator overloading.

This is the original version of overloading operator /=

template<typename T>
Matrix<T> Matrix<T>::operator /= ( double varValue)
{
    for (int i=0;i<this->rows;i++)
    {
        for (int j=0;j<this->columns;j++)
        {
            datavector.at(i).at(j) /= varValue;
        }
    }
    return *this;
}

I wanted to change code above into something like this

template<typename T>
Matrix<T> Matrix<T>::operator /= ( double varValue)
{
    BOOST_FOREACH(vector<T> row,datavector)
    {
        BOOST_FOREACH(T item,row)
        {
            item /= varValue;
        }
    }
}

However I constantly get an error

T: illegal use of this type as
expression

Is there any way to fix that?

Answer 1

You need to use a reference (based on the example at http://www.boost.org/doc/libs/1_39_0/doc/html/foreach.html). Also, you were missing a return statement:

template<typename T>
Matrix<T> Matrix<T>::operator /= ( double varValue)
{
    BOOST_FOREACH(vector<T> &row,datavector)
    {
        BOOST_FOREACH(T &item,row)
        {
            item /= varValue;
        }
    }
    return *this;
}