C++ lambda with captures as a function pointer

Question

I was playing with C++ lambdas and their implicit conversion to function pointers. My starting example was using them as callback for the ftw function. This works as expecte

Answer 1

There is a hackish way to convert a capturing lambda into a function pointer, but you need to be careful when using it:

https://codereview.stackexchange.com/questions/79612/c-ifying-a-capturing-lambda

Your code would then look like this (warning: brain compile):

int main()
{

    vector entries;

    auto const callback = cify([&](const char *fpath, const struct stat *sb,
        int typeflag) -> int {
        entries.push_back(fpath);
        return 0;
    });

    int ret = ftw("/etc", callback, 1);

    for (auto entry : entries ) {
        cout << entry << endl;
    }

    return ret;
}