Question

In C++ - The Complete Reference, the author gives us a challenge after showing how he implements a custom C++ string class. Excerpt from the book:

A Challenge:
Try implementing StrType (the string class) using the STL. That is, use a container to store the characters that comprise a string. Use iterators to operate on the strings, and use the algorithms to perform the various string manipulations.

I understand the basic concept here, but am having trouble implementing it. should I do std::vector < char > and push_back for every char or something like that? What about the string manipulations? Need some help. Sample code will be accepted gratefully, or you can explain how I may be able to implement this.

Answer 1

Yes, std::vector<char> sounds like a great idea. It will save you from the troubles of writing a custom destructor, copy constructor and copy assignment operator. Plus all the iterator member functions (begin, end and co.) can just delegate to the std::vector<char> versions.

can u give some code on how to do string manipulations? e.g concatenation ?

Sure thing, here is how I would overload operator+= and operator+ for the string type:

class StrType
{
    std::vector<char> vec;

public:

    // ...

    StrType& operator+=(const StrType& rhs)
    {
        vec.insert(vec.end(), rhs.vec.begin(), rhs.vec.end());
        return *this;
    }
};

StrType operator+(StrType lhs, const StrType& rhs)
{
    lhs += rhs;
    return lhs;
}

There’s probably a more efficient version of operator+, but you can figure that out on your own.