Assigning vector::iterator to char array post VS 2003

Question

I am trying to get some C++ code originally written in Microsoft Visual Studio (VS) 2003 to compile under VS 2008 and I am having trouble finding an efficient solution to assigning a vector::iterator to the beginning of a char array. I know that iterators went from being a defined as a simple pointer type (T*) to a class type between VS 2003 and VS 2005. Here is a simple example of what I am talking about:

typedef std::vector<char>       CharContainer;
typedef CharContainer::iterator InputIt;

int FindNumMsgs( InputIt _inputIter, int _len );

int ProcessBufferForMsgs( char buf[], const size_t maxlen )
{
    int numMsgs = FindNumMsgs( InputIt(buf), maxlen );
    ...
}

So, in VS 2003, this compiles and works with no problem (since iterators are defined as T*). In VS 2008, this errors with C2440 (function-style-cast) since I can no longer just assign the iterator with the buf pointer. What would I do to get this to work in VS 2008 now that iterators are a class type? I could copy the buffer into a vector, then pass in myVec.begin(), but I have to think that I can avoid this overhead.

Answer 1

If FindNumMsgs accepts char* as the first parameter, maybe you could just use a simple char* pointer:

int ProcessBufferForMsgs( char buf[], const size_t maxlen )
{
    char* simpleIterator = buf;
    int numMsgs = FindNumMsgs( simpleIterator, maxlen );
    ...
}

Answer 2

What's the signature of FindNumMsgs? If it takes a char* you can just replace InputIt(buf) with buf. If it doesn't, there's little you can do about it without changing FindNumMsgs.

Answer 3

Time to refactor. You need to change FindNumMsgs to take a (const?) char * as input, or maybe provide a second overloaded version. Better yet make it a templatized function that takes a begin/end pair of anything with iterator or pointer semantics.

Answer 4

The proper solution would be to template FindNumMsgs such that it can work with either iterators or pointers (since pointers can be used as iterators just fine). Something like this:

template <class T>
int FindNumMsgs(T it, int count) {
    while(count--) {
        // do whatever
        it++;
    }
    return n;
}