convert vector into char** C++

Question

I have a vector variable. I need to pass it onto a method which accepts char**as an input parameter.

how to do this ? If

Answer 1

Galik's answer has a number of safety issues. Here is how I would do it in Modern C++:

#include 
#include 
#include 

void old_func(char** carray, std::size_t size)
{
    for(std::size_t i(0); i < size; ++i)
        std::cout << carray[i] << '\n';
}

void other_old_func(const char** carray, std::size_t size)
{
    for(std::size_t i(0); i < size; ++i)
        std::cout << carray[i] << '\n';
}

int main()
{
    {
        std::cout << "modifiable version\n";
        std::vector strings{"one", "two", "three"};
        std::vector cstrings{};

        for(auto& string : strings)
            cstrings.push_back(&string.front());

        old_func(cstrings.data(), cstrings.size());

        std::cout << "\n\n";
    }
    {
        std::cout << "non-modifiable version\n";
        std::vector strings{"four", "five", "six"};
        std::vector cstrings{};

        for(const auto& string : strings)
            cstrings.push_back(string.c_str());

        other_old_func(cstrings.data(), cstrings.size());
        std::cout << std::endl;
    }
}

No messy memory management or nasty const_casts.

Live on Coliru.

Outputs:

modifiable version
one
two
three


non-modifiable version
four
five
six