// Assignment operator
MyString& MyString::operator=(const MyString& cSource)
{
    // check for self-assignment
    if (this == &cSource)
        return *this;

    // first we need to deallocate any value that this string is holding!
    delete[] m_pchString;

    // because m_nLength is not a pointer, we can shallow copy it
    m_nLength = cSource.m_nLength;

    // now we need to deep copy m_pchString
    if (cSource.m_pchString)
    {
        // allocate memory for our copy
        m_pchString = new char[m_nLength];

        // Copy the parameter the newly allocated memory
        strncpy(m_pchString, cSource.m_pchString, m_nLength);
    }
    else
        m_pchString = 0;

    return *this;
}

The first problem is the line “delete[] m_pchString;”. If “m_pchString” is not allocated, could this cause an exception? Would it not be better to check if “m_pchString” is valid before attempting to delete the memory?

The second problem occurs if “cSource.m_pchString” is a zero length string. Would it not be better to assign NULL to m_pchString if “cSource.m_pchString” has zero length? Oh, and what happens when an attempt is made to create a zero length string in the “new” statement and when “strncpy” attempts to copy a zero length string?

Otherwise this code is a good learning tool.

Phil

7 + 8 – 3 * 7 = 15 – 21 = -6, the answer given by output is perfectly correct.