Remove delete/delete[]

Question

I'm trying to remove all the delete and delete[] of an old application and use smart pointers instead. In the following code snippet, I want to remove the last for cicle.

std::unique_ptr<MapiFileDesc> fileDesc(new MapiFileDesc[numFiles]);

for (int i = 0; i < numFiles; ++i)
{
    // Works but I've to delete[] at the end
    fileDesc[i].lpszPathName = new CHAR[MAX_PATH];

    // Does not work. For each iteration the previous array will be deleted
    // It also happens with shared_array
    boost::scoped_array<CHAR> pathName(new CHAR[MAX_PATH]);
    fileDesc[i].lpszPathName = pathName.get();
}

// I want to remove the following cicle
for (int i = 0; i < numFiles; ++i)
{
    delete [] fileDesc[i].lpszPathName;
    fileDesc[i].lpszPathName = nullptr;
}

What do you think it is the best approach for this situation: use a wrapper object that will keep track of all the arrays created and delete them in the destructor OR use a vector of boost::shared_array and assign them to each of the elements?

std::vector<boost::shared_array<CHAR> > objs;

for (int i = 0; i < 10; ++i)
{
    objs.push_back(boost::shared_array<CHAR>(new CHAR[MAX_PATH]));
}

I need to use boost::shared_ptr since I'm using VC++ 2008

Thanks in advance. J. Lacerda

Answer 1

std::vector<std::string > objs(numFiles, std::string(MAX_PATH, 0));
std::vector<MapiFileDesc> fileDesc(numFiles);
for (int i = 0; i < numFiles; ++i)
    fileDesc[i].lpszPathName=objs[i].data();
// after the C API calls, if you do need to use the strings as C++ strings,
// resync the C++ string length with the C string data
// (not necessary if you just use them via c_str())
for (int i = 0; i < numFiles; ++i)
    objs[i].resize(strlen(objs[i].c_str());

By the way, if you don't need to pass the whole array to C APIs but just single structs, you can make a single vector of a struct that stores both the MapiFileDesc structure and the std::string, binding strongly the lifetime of both objects and allowing the constructor to take care of linking lpszPathName with the string data() member; still, probably I wouldn't bother if this structure is used just in a single function.